cics mainframes

8/9/2019 cics mainframes

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CICS(Customer Information Control System)


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Table of Contents

Introduction to CICS

Basic Mapping Support

Program Control

File Processing Error Handling

Queues

Interval and Task Control

Recovery and Restart Program preparation

CICS Supplied Transactions

Case Study


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Introduction to CICS

Customer Information Control System -CICS developed in late1960s as a DB/DC control system

CICS provides an interface between the Operating System and

application programs Macro Level CICS - initial version Assembler macro to request

CICS services

Command Level CICS - high level lang.version - commands torequest CICS services - Single command can replace series of

macros


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Batch & Online : Differences

BATCH SYSTEM2. Input data is prepared and

given in sequence (file)3. Processing sequence is

predictable and hencerestarting the process in caseof failure is easy.

4. Programs and files cant beshared

5. Programs are scheduledthrough jobs

6. O/P printed on paper or insequential of VSAM or Indexedfiles

7. Response time: Could be

scheduled to be Hours or days

ONLINE SYSTEM2. Data is entered as needed not

in sequence (terminal)3. Since processing sequence is

unpredictable, specialrecovery/restart proc. isrequired in case of failure

4. Programs and files can beshared

5. Transaction can be run at anytime

6. O/p displayed on Terminalupdated files

7. Response Time: Could be inminutes or second. Usually in

seconds


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CICS & Operating System

Operating SystemOperating System

CICSCICS

Users

App.Files &

Database

EnterCode :


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DB/DC System

Terminals

Central System

Data

Base

CICS SystemEnvironment &API routines,and Application

Programs


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CICS System Services

Data-Communication Functions

Data-Handling Functions

Application Program Services

System Services

Monitoring Functions


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Task :- A basic unit of work which is scheduled by the

operating system or CICS

Ex -Read from and write to the terminal

Transaction :- An entity which initiates execution of a task. InCICS, transaction is identified by the transaction identifier(Trans-id)

Task & Transaction


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Application Programming

Concepts

Pseudo-Conversational

Multitasking

Multithreading

Quasi-Reentrancy


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Conversational : A mode of dialogue between program andterminal based on a combination of sending message andreceiving message within the same task

Since human response is slower than the CPU speed, a

significant amount of resource will be wasted just waiting

Pseudo-Conversational. A mode of dialogue between programand terminal which appears to the operator as a continuousconversation but which is actually carried by a series of tasks

Terminal Conversation


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PROCEDURE DIVISION.:FIRST-PROCESS.

EXEC CICS RECEIVE ----


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Transaction TSK1Program PROG1

PROCEDURE DIVISION.:

EXEC CICS RECEIVEEND-EXEC.

:EXEC CICS SEND

END-EXEC.EXEC CICS RETURN

TRANSID (TSK2)END-EXEC.

Transaction TSK2Program PROG2

PROCEDURE DIVISION.:

EXEC CICSRECEIVE

END-EXEC.:

EXEC CICS SEND

END-EXEC.EXEC CICS RETURNEND-EXEC.

Pseudo-Conversation Example


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Control Programs (or Management Modules)

Programs that interface between OS and app. pgm

Handle the general functions that are crucial to operation of

CICS Control Tables

Define the CICS environment

Functionally associated with the management module

Control Blocks (or Areas)Contain system type information. Eg. Task Control Area

contains information about the task

CICS Components


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Programs

Program Control PCP

File control FCP

Terminal Control TCP

Task Control KCP

Temporary Storage TSP

Transient Data TDP

Storage Control SCP

Interval Control ICPJournal Control JCP

Tables

Processing ProgramTable PPT

File Control Table FCTTerminal Control Table TCTProgram Control Table PCTTemp. Storage Table TSTDestin. Control Table DCT

Mangement Pgms & Ctrl Tables


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CICS Program Considerations

Considerations:

Must eventually return control to CICS

Cant modify procedure division instructions because CICSprograms may be shared by many tasks

Can modify working storage since a unique copy of workingstorage is created for each task


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CICS Program Restrictions

Restrictions:

No CONFIG. SECTION, I/O SECTION to be specified in theENVIRONMENT DIVISION.

FILE SECTION, OPEN, CLOSE, and non-CICS READ & WRITEstatements are not permitted because file management is handledby CICS.

COBOL commands such as ACCEPT, DISPLAY, EXHIBIT,TRACE, STOP RUN, GOBACK are avoided. (STOP RUN &GOBACK are sometimes included in order to eliminate compilerdiagnostic but never executed)


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Sample CICS Program

IDENTIFICATION DIVISION.

PROGRAM-ID. SAMPLE.

ENVIRONMENT DIVISION.

DATA DIVISION.WORKING-STORAGE SECTION.

01 WS-INPUT.

05 WS-TRANSID PIC X(4).

05 FILLER PIC X(1).

05 WS-IN-EMP-CD PIC X(4) VALUE ALLX.


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Sample Program (Contd..)

01 WS-OUTPUT.05 FILLER PIC X(16) VALUE EMP CODE : .05 WS-OUT-EMP-CD PIC X(4).

01 WS-LENGTH PIC S9(4) COMP.

LINKAGE SECTION.CAN Include DFHCOMMAREA if data needs to be communicatedbetween two transactions or multiple iterations of the same

transaction.PROCEDURE DIVISION.

000-MAINLINE.PERFORM 100-RECV-INPUT.PERFORM 200-SEND-OUTPUT.EXEC CICS RETURN END-EXEC.


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100-RECV-INPUT. MOVE 9 TO WS-LENGTH.

EXEC CICS RECEIVEINTO (WS-INPUT) LENGTH (WS-LENGTH)

END-EXEC.MOVE WS-IN-EMP-CODE TO WS-OUT-EMP-CODE

200-SEND-OUTPUT. EXEC CICS SEND

FROM (WS-OUTPUT) LENGTH (20)

ERASEEND-EXEC.

Sample Program (Contd..)


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The CICS translator converts CICS commands into the COBOLcode so that it could be compiled by a Standard Cobol compiler

CICS program with CICS

CommandsCICS Translator

COBOL Statements

CICS Translator


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When you compile a CICS/VS program the translator willautomatically add many lines of code to your program, which can

be seen in the compiled listing

Translator


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Basic Mapping Support


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Topics in BMS

Introduction to BMS

Map and Mapset

Physical and Symbolic Map

Map Definition Macros

Screen Manipulation/Handling

Screen Design Considerations

Interfacing with Terminal using a Map


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Introduction to BMSIntroductory concepts

In online systems, formatted screens are used. In order todisplay formatted screen, a terminal (e.g. 3278) mustreceive a series of data stream called Native Mode DataStream (NMDS) based on the hardware protocol; thisNMDS is a mixture ofBuffer Control Characters (BCCs)and text data. NMDS is designed for a particular terminaland is thus both device dependent and format dependent.So if NMDS is used, re-coding is required whenever there is

change in the terminal device or screen format. To removethis device and format dependency from applicationprogram, CICS provides a facility called Basic MappingSupport (BMS).


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Removal of device dependent codes from Application Program

Removal of constant information from Application program(Headers, Titles...)

Construct NMDS - Native Mode Data Stream

Text handling

Terminal Paging & Message routing

Contents of the screen defined thru BMS is called Map.

Map is a program written in assembly language.

BMS macros are available for Map coding.

The BMS Macros are coded in the form of Maps, and Mapsets todefine the screen attributes, screen field positions, and fieldcharacteristics.

Primary Functions of BMS


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Map and Mapset

Representation of one screen format is called Map (screen

panel).

One or more maps, link edited together, makes up a Mapset

(load module).

Mapset must have a entry in PPT as given below:

DFHPPT TYPE=ENTRY,MAPSET=nameOr DFHPPT TYPE=ENTRY,PROGRAM=name


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Mapset name has two parts.

Generic name 1- 7 chars. Used in App. Program.

Suffix 1 char. To identify the device type

Multimap Panel

Dynamically constructing a screen panel with multiple maps at

the execution time

Map and Mapset (Contd..)


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The concepts of map and mapset can be utilized in twotype of cases as given below:

Case 1: A mapset consist of a single map. For e.g.

MAPSET1 MAPNUM1

Case 2: A mapset consists of several maps. For e.g.

MAPSET2 MAPNUM1

MAPNUM2

Map and Mapset (Contd..)


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Types of MAPSThere are 2 types of MAPS

Physical Map

Physical Map is a map used by CICS (CSECT)

Ensure device independence in the application program

BMS macro coding ==> Assembly==> Link edit ==> Load module ==>LOADLIB ===> To be used by CICS

Symbolic Map

Ensure device and format independence in the application programSymbolic Map is a map used by Application Program (DSECT)

BMS macro coding ==> Assembly ==> Symbolic map definition ==>COPYLIB ==> Copied (COPY) into CICS application program.


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01 EMPRECI.02 FILLER PIC X(12).02 EMPNAL PIC S9(4) COMP.02 EMPNAF PIC X.

02 FILLER REDEFINES EMPNAF.03 EMPNAA PIC X.

02 EMPNAI PIC X(21).

01 EMPRECO REDEFINES EMPRECI.

02 FILLER PIC X(12).02 FILLER PIC X(03).02 EMPNAO PIC X(21).

Example Symbolic Map


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Physical & Symbolic Map - Logic Flow

BMS

source

Assembler

Physical MAP

Linkage editorSymbolic MAP

Load module (MVS)


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Physical Map.

The BMS macros are assembled and link-edited into CICS loadlibrary to create the physical map. The mapset like any other CICSprogram is stored in CICS runtime library the PPT(Program

Processing Table). At the program execution time the physicalmap is being used by CICS to load the screen image.

In case of input operations, the physical map defines themaximum length, the starting position for each field to be read and

allows BMS to interpret an input NMDS.

In case of output operations, the physical map defines the startingposition, length, field characteristics and the default data for eachfield and allows BMS to construct an output NMDS.

Physical Map


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The symbolic map is coded using the BMS macro, assembledseparately and catalogued into a copy library. The symbolic mapserves as a DSECT for referencing the Terminal Input/Output Area(TIOA). The program issues a COBOL COPY statement to include it

in the program.

The symbolic maps represents the actual data structure of the fieldsdefined in the physical map, and is used by the application programto send and receive information from the terminal, in the CICSSEND-MAP & RECEIVE MAP commands.

The symbolic map can be used by the CICS application programs todynamically to alter the field attributes, modify screen cursor

position, and highlight , protect , unprotect specific fields on thescreen.

Symbolic Map


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Map definition Macros

General FormatColumn Number1 16 72setname operation operands contd.

ExampleEMPMAP DFHMSD TYPE=MAP, X

MODE=INOUT, XLANG=COBOL, XSTORAGE=AUTO, X

TIOAPFX=YES** ANY COMMENTS


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Explanations:

SETNAME : Name of the mapset. Used in CICS commandto read or write one of the maps in the mapset. Itis the load module name.

OPERATION : Macro identifier. Mapset/Map/Field definition.

OPERANDS : Optional key words (parameters)separated by comma.

CONTD : Current line can be continued by leaving

this column non-blank (usually X) andthe next line have to be started in16th column.

Comments : * in column 1 makes the line comment.

Map definition Macros (Contd..)


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INITIAL VALUES : Always surround initial valuesby single quote marks

Escape Chars : and &

Map definition Macros (Contd..)


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Order of Macros

DFHMSD TYPE=DSECT Mapset

DFHMDI Map

DFHMDF A field

DFHMDF A field:

DFHMDI Map

DFHMDF A field

DFHMDF A field

:

DFHMSD TYPE=FINAL Mapset

END


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DFHMSD Macro

The DFHMSD macro is used to define a mapset (TYPE=MAP)and its characteristics or to end a mapset definition(TYPE=FINAL). Only one mapset is allowed in one assemblyrun. All the maps in a map set get assembled together, andthey're loaded together at execution time.

Example:TSTMSET DFHMSD TYPE=&SYSPARM, X

MODE=INOUT, XLANG=COBOL,

X STORAGE=AUTO, XTIOAPFX=YES,

XCNTL=(FREEKB,FRSET,PRINT)


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Options

TYPE= To define the map type

DSECT For symbolic map

MAP For physical map

&SYSPARM For special assembly procedure

FINAL To indicate the end of a mapsetcoding

MODE= To indicate input/output operations

IN For an input map only

OUT For an output map only

INOUT For maps involving both input and

output.

DFHMSD Macro (Contd..)


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STORAGE =

AUTO To acquire a separate symbolic map area foreach mapset

BASE To have the same storage base for the symbolic

maps of from more than one mapset

TIOAPFX=

YES To reserve the prefix space (12 bytes) forBMS

commands to access TIOA properly. Requiredfor the CICS command level.



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CNTL= To define the device controlrequests

FREEKB To unlock the keyboardFRSET To reset MDT to zero status

ALARM To set an alarm at screen display timePRINT To indicate the mapset to be sent to the

printer

TERM=type This ensures device independence,required if other than 3270 terminal is beingused

SUFFIX=nn To specify the user provided suffix number.This must correspond to the TCT

parameter.



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DFHMDI Macro

Defines a map and its characteristics

Example

EMPMAP DFHMDI SIZE=(ll,cc), XLINE=nn, XCOLUMN=mm, XJUSTIFY=LEFT/RIGHT

Options

SIZE=(ll,cc) To define the size of the map by the line size (ll)and the column size (cc). Useful when the screen

contains.LINE Indicates the starting line number of the map.

COLUMN Indicates the starting column number of the map.

JUSTIFY To specify the entire map (map fields) is to be left or

right justified.


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The DFHMDF macro is used to define a field in a map and itscharacteristics. This is the position on the screen where the fieldshould appear. It's the position relative to the beginning of themap. Field starts with its attribute byte, so if POS=(1,1) is coded,

then the attribute byte for that field is on line 1 in column 1, andthe actual data starts in column 2. The length of the field (notcounting the attribute byte) is specified. Literals can be specifiedwithin quotes; these character data is for an output field. It isused to define labels and titles for the screen and keep them

independent of the program.

DFHMDF Macro


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Sample Screen layout

The above defines the screen layout as given below:

Where

& Is the Attribute character

n Is unprotected numeric_ Is Cursor

ITEM NUMBER :&nnnnnnnn


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DFHMDF

Macro For The Above LayoutDefine a field and its characteristics

Example

DFHMDF POS(ll,cc), X

INITIAL=Customer No. :, XATTRB=ASKIP, X

LENGTH=14

CUSTNO DFHMDF POS=(ll,cc),X

ATTRB=(UNPROT,NUM,FSET,IC), X

JUSTIFY=RIGHT, X

PICIN=9(8), X

PICOUT=9(8), X

LENGTH=8


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Attribute character

Function:

The attribute character is an invisible 1-byte character, whichprecedes a screen field and determines the characteristics of afield.

ASKIP Autoskip. Data cannot be entered in this field. The cursorskips to the next field.

PROT Protected field. Data cannot be entered into this field. Ifdata is entered, it will cause the input-inhibit status.

UNPROT Unprotected field. Data can be entered and this is usedfor all input fields.

NUM Numeric field. Only numbers (0 to 9) and special characters(. and -) are allowed.


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Attribute character (Contd..)

BRT Bright display of a field (highlight).

NORM Normal display.

DRK Dark display.

IC Insert cursor. The cursor will be positioned in this field. Incase, IC is specified more than once, the cursor is placed inthe last field.

FSET Field set. MDT is set on so that the field data is to be sentfrom the terminal to the host computer regardless of

whether the field is actually modified by the user.


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Modified Data Tag

Function:

Modified Data Tag (MDT) is a one bit of the attributecharacter. If it is off (0), it indicates that the terminaloperator has not modified the field. If it is on (1), it

indicates that the operator has modified this field. Onlywhen MDT is on, the data of the field will be sent by theterminal hardware to the host computer. An effectiveuse of MDT drastically reduces the amount of datatraffic in the communication line and thus improvesperformance.

Three ways of setting and resetting the MDT.

1. Terminal user modifies a field on the screen, it isautomatically set to 1 (on) by the terminal hardware.


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Modified Data Tag (Contd..)

2. If CNTL=FRSET is specified in the DFHMSD or DFHMDImacro, when the mapset or the map is sent to the terminal,MDT will be reset to 0 (off) i.e. not modified for all the

fields of the mapset or the map.

3. If FSET is specified in the ATTRB parameter of theDFHMDF macro for a field, when the map is sent to theterminal, MDT will be set to 1. (on i.e. modified) for the fieldregardless of whether the field has been modified by theterminal user.


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Skipper Technique

Unlabelled 1-byte field with the autoskip attribute

DFHMDF POS(ll,cc),ATTRB=ASKIP,LENGTH=1

To skip the cursor to the next unprotected field after oneunprotected field.

Screen Layout :

&xxxxx&$ &xx

where

$ Skipper field

& Attribute byte

X Unprotected field


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Stopper Technique

Unlabelled 1-byte field with the protect attribute

DFHMDF POS(ll,cc),ATTRB=PROT,LENGTH=1

To stop the cursor in order to prevent erroneous field overflow byterminal user.

Screen Layout :

&xxxxx&$#&$

where

# Stopper field


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Format Of the Symbolic Map

Format of Symbolic Map

Once the symbolic map is assembled and is placed inthe COPY library, the COBOL COPY statement can beused to include it in the application program.

The symbolic map starts with the 01 level definition ofthe map name specified in the DFHMDI macro with thesuffix I for the input map and the suffix O for the

output map.

Next is the definition of FILLER PIC X(12), which is theTIOA prefix created by the TIOAPFX=YES of the DFHMSDmacro; this is required by the BMS under the CICS

command level.


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(Contd..)For each field name (1 to 7 characters) specified in theDFHMDF macro, BMS creates three fields for inputs andthree fields for outputs, by placing one character suffix tothe original field name. The meaning of these fields are

given below:

Name + L: The half-word binary (PIC S9(4) COMP)field. For the input field, the actual number ofcharacters typed in the field will be placed by the BMSwhen the map is received. For the output field, this isused for the dynamic cursor positioning.


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(Contd..) Name + F: Flag Byte. For the input field, it will be

X80 if the field has been modified but no data issent (i.e. the field has been cleared). Otherwise thisfield is X00.

Name + A: The Attribute byte for both input andoutput fields.

Name + I: The input data field. X00 will be

placed if no data is entered. Note that space X40is data. The application program should differentiateX00 from space (X40).

Name + O: The output data field.


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Example Of Symbolic Map

01 EMPRECI.02 FILLER PIC X(12).

02 EMPNAL PIC S9(4) COMP.

02 EMPNAF PIC X.02 FILLER REDEFINES EMPNAF.

03 EMPNAA PIC X.

02 EMPNAI PIC X(21).

01 EMPRECO REDEFINES EMPRECI.02 FILLER PIC X(12).

02 FILLER PIC X(03).

02 EMPNAO PIC X(21).


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Cursor Positioning Techniques

CICS provides multiple ways of to specify where toposition the cursor on the screen. The cursor positioningis important to prompt an user of an entry he has tomake, or to point to an error which has occurred during

editing the user entries.

Static positioning (Achieved thru Map definitionATTRIB=IC).

Example :DFHMDF

POS=(5,8),ATTRB=(UNPROT,FSET,IC),LENGTH=10


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Cursor Positioning Techniques(Contd..)

Dynamic/Symbolic Positioning.

The cursor is placed dynamically through an

application program by moving -1 to thesymbolic map field-length field (i.e. fieldname +L) for the field where the cursor is to be placed. The SEND MAP command must be issued withthe CURSOR option (without value). Also, the

mapset should be coded with MODE=INOUT inthe DFHMSD macro. This approach is veryuseful when the cursor is to be placed at thefield where data entry error has been detectedby the data edit routine.


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Example Of Dynamic Cursor Positioning.

WORKING-STORAGE SECTION.

:COPY MAPSET1

01 MAPSET1I

05 FILLER PIC X(6).

05 FIELD1L PIC X(5).

05 FIELD1F PIC X.05 FIELD1I PIC X.


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PROCEDURE DIVISION.

: MOVE 1 TO FIELDL.

EXEC CICS SEND MAP(MAP1)

MAPSET(MAPSET1)

CURSOR

ERASE

END-EXEC.

The cursor will be placed at FIELD1 field of the map

during execution.


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Dynamic/Relative Positioning (application program)

The cursor is placed dynamically through an application programusing the CURSOR(data-value) option in the SEND MAP

command with the value of the relative position (starting fromzero) of the terminal. At the completion of the SEND MAPcommand, the map will be displayed with the cursor placed atthe specified position, overriding the static cursor positiondefined at the map definition time.


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Example EXEC CICS SEND

MAP(MAP1)

MAPSET(MAPSET1)

CURSOR(100)

ERASE

END-EXEC.

The cursor will be placed at FIELD1 field of the map MAP1during execution.


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Interfacing with a Terminalusing a Map

The BMS maps are used in the application programs forthe actual terminal input/output operation. Theseoperations are performed by a set of CICS commandsfor BMS.

The following are the three basic functionsperformed by CICS commands:

Map Sending function using the data in the symbolic map,BMS prepares the output NMDS, the corresponding physicalmap, and sends to the terminal.

Map Receiving Function using the input NDMS from theterminal, BMS prepares data in the symbolic map through thecorresponding physical map.

Text Handling Function BMS prepares text without using a

map and sends to the terminal.


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Interfacing with a Terminalusing a Map (Contd..)

Flow of Information from 3270 Terminal and the Application Program.

ApplicationProgram

Send MapCommand

SymbolicMap

BMS

PhysicalMap

BMSSymbolicMap

ApplicationProgram

Receive MapCommand

OutputNDMS

InputNDMS

Terminal

DataEntry

Terminal


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Interfacing with a Terminalusing a Map (Contd..)

The following are the available commands:

RECEIVE MAP : To receive a map

SEND MAP : To send a map SEND CONTROL : To send a control function to the

terminal

SEND TEXT : To send a text

SEND PAGE : To send the accumulated text or

maps as a logical message


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Receive Map Command

RECEIVE MAP Command is used to receive input from a terminal.At the completion of the command, the symbolic map will containvalid data from the terminal in the following three fields as per eachfield defined by the DFHMDF macro:

Field name + L : The length field, which contains the actual

number of characters, typed in the screenfield.

Field name + F : The Flag Byte which is normally X00. It will

be X80 if the field has been modified butcleared.

Field name + I : The actual input data field. X00 will be placedif no data is entered.


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Receive Map Command(Contd..)

Syntax: EXEC CICS RECEIVEMAP (MAPNAME)MAPSET(MAPSETNAME)

[ SET(POINTER)|INTO(DATANAME) ][ LENGTH(MSG-LEN)]

[ HANDLE | NOHANDLE ][ RESP() ]

END-EXEC. Conditions: INVREQ, MAPFAIL


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MAP specified the name of the MAP defined thru DFHMDIcommand , which describes the screen details.

MAPSET specified the name of the MAPSET defined thru DFHMSDcommand which includes the MAP.

INTO is used to specify the area in the working storage section towhich the data from the terminal is to be placed.

SET is used when the address pointer is to be set to the address ofthe symbolic map (by CICS) so that the application program candirectly refer to the record without moving the record content into theworking storage area defined in the program.


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RESP will be used by CICS to place a response code at acompletion of the command.

HANDLE is used to transfer control to the procedure labelspecified if the exceptional condition specified occurs.

NOHANDLE will cause no action to be taken for any exceptionalcondition occurring during execution of the CICS command.

Conditions :INVMPSZ , INVREQR , LENGERR, MAPFAIL

MAPFAIL is set when the data being mapped has a lengthof zero. It occurs when the following keys are pressed inresponse to the RECEIVE MAP command: CLEAR orAttention Keys & ENTER or PF keys without enteringdata.


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SEND MAP Command

The SEND MAP command is used to send formatted output toa terminal. Before issuing this command, the applicationprogram must prepare the data in the symbolic map of themap to be sent, which has the following three fields per each

field defined by the DFHMDF macro:

Name + L: The length field, for which the applicationprogram need not prepare except when used for the dynamiccursor positioning.

Name + A: The Attribute byte for output fields.Application program will use it for dynamic cursor positioning.

Name + O: The actual output data field, where the

application program places the data.


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SEND MAP Command (Contd..)

EXEC CICS SEND MAP(MAP1)

MAPSET(MAPSET1) ]

[FROM(DATANAME) ], [DATAONLY] |MAPONLY],

[ CURSOR(VALUE) ],[ FREEKB ] , [ ERASE ] , [ FRSET ] ,

[ HANDLE | NOHANDLE ] ,

[ RESP (DATANAME) ]

END-EXEC.

Conditions : INVREQ,LENGERR


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MAP specified the name of the MAP defined thru DFHMDI command, which describes the screen details.

MAPSET specified the name of the MAPSET defined thru DFHMSDcommand which includes the MAP.

MAPONLY is used when no data from your program is to be mergedinto the map.

DATAONLY is used when only the data from the program is to besent to the screen. The constants in the map are not sent.


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FROM is used to specify the area in the working storage sectionfrom which the data is to be sent to the terminal.


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AID KEYS

First time when a transaction is initiated the application programthrows the screen image on the terminal thru SEND MAP command.Once the screen appears, the AID (Attention Identifier ) Keys arebeing used to send the information back from the terminal to CICS toapplication program. CICS application program needs to trap theattention identifier keys and process various functions related to theAID keys.

Salient Points

PF keys, PA keys, ENTER & CLEAR key

EIBAID in the CICS Executive Interface Block contains, recentlyused AID key.


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AID KEYS (Contd..) DFHAID CICS System copybook which stores the values of

the EIBAID field for the various AID keys. Flow : User hitsAID key Control goes to CICS To Application program.EIBAID contains information about the last AID key pressed.Program compares EIBAID to the DFHAID field and

performs processing logic as per the AID key pressed.

HANDLE AID establish the routines that are to be invokedwhen the aid is detected by a RECEIVE MAP command.Syntax : EXEC CICS HANDLE AID

Option (label)END-EXEC

Conditions : INVREQ


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Functional Screen Design

Screen layout should be similar to source where terminalusers enter data.

Screen id should be placed at the top right corner of ascreen. This helps at problem determination time.

Screen title and field descriptions should be self-explanatory.Instructions should be concise.


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Screen Design Considerations(Contd..)

Large fields can be broken into a number of small fields. E.g.the field contact information can be split into contactnumbers, email ids and postal address.

In case of repeated fields or group of fields, sequencenumbers helps.

Error messages should be provided. Preferably the last fewlines can be used for the error messages.


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User-Friendly Screen Design

Screens should be simple and friendly.

Default values in fields helps in reducing keystrokes by theusers. Also, in case the user forgets to enter a field data,

defaults values are assigned according to the field. Calculations should be done by program and not by users.

The cursors should be placed in the appropriate fields.

Highlight the error field. Using a different colour or blinkingthe error field can achieve this. This enables users to identify

the erroneous field easily.


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Alarm sound can be used for error entries.

Provide suitable help messages for erroneous entries. Thehelp message should be instructive and kind and should notbe rude.

Provide help on fields and their meanings. Using an attentionkey for a help menu, which has details on each field, makesa screen user-friendly.

Artistic Screen Design

A simple screen layout is always preferred. Proper use of indentations, spaces, and lines makes a

screen look good.


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Colour can help in improving the screen design; however thecolour used should be in accordance with the norms andstandards followed.

Considerations for Human Errors Important and useful fields can be placed at the top part of

the screen.

Related fields can be grouped together.

Protected fields should be skipped automatically. This

reduces manual skipping and is preferred. Skipper/Stopper techniques can be used at appropriate

places.


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Exercise - 1

Exercise - 1


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CICS File ProcessingTechniques


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CICS VS FILE PROCESSING

File handling in CICS is achieved thru a set of file handlingcommands. It is essential to know the various file handlingcommands for application programming.

File Specific functions to be performed are the following. Defining a specific file to the CICS system. Reading a file sequentially

Reading a Key Sequenced file randomly

Reading a file sequentially starting from a specific point.

Reading and Updating a record Deleting a Record.

Handle any errors that occur during file processing


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CICS VS FILE PROCESSING

Instead, CICS has a list of all the files it is allowed

To access.

This list is called the FILE CONTROL TABLE

(FCT) and is maintained by the systems

programmers

When CICS/VS is started up. It goes through the

FCT and makes all the files available. When

CICS/VS is closed down it closes all the files.

Application programs do not need

The FD Section, and the Input Output

Section. Application program directlyRefer to filenames in EXEC CICS

Command.

Files do not need to exclusively

defined in Application

programs. The files do not need

to opened and closed in a CICS

application program , before

being used in the program.


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CICS COBOL V/S COBOL

BATCH COBOL CICS

COBOL

READ DATAFILE INTO REC-AREA EXEC CICS READ

DATASET (FILE IDENTIFIER)

INTO (RECORD NAME)RID-FLD (record-key)

END-EXEC.

WRITE RECORD-NAME FROM

RECORD-AREA

EXEC CICS WRITE

DATASET (File identifier)

FROM (Record-Name)RID-FLD (Record- key)

END-EXEC.

Replaced by

Replaced by

AT END MOVE Y TO

EOF-FLAG


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VSAM

Different types of VSAM Datasets used in CICS are :

ESDS Entry Sequenced Dataset KSDS Key Sequenced Dataset

RRDS Relative Record Dataset


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Services Provided By CICS

Basic Operations required for a file are

Adding a Record.

Modifying an Existing Record.

Deleting an Existing Record.

Browsing One or Selected or All Records.

In Addition, CICS Provides

Exclusive Control. (Record Level Locking).

Data Independence.Journaling.

Opening and closing Files.


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Defining Files

In CICS, files cannot be created. Files can be created usingIDCAMS Utility.

Re-indexing, Creating new indexes, etc. should be done usingIDCAMS Only.


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Defining A File in CICS

Files should be defined in FCT (File Control Table).

FCT will contain all the Information about a file (like datasetname, access methods, permissible file service request, etc.)

Defining files can be done either by CEDA Transaction orDFHFCT Macro.


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Syntax of DFHFCT Macro

DFHFCT TYPE=FILE,ACCMETH=VSAM,

DATASETNAME=NAME,

SERVRQ=(ADD,BROWSE,DELETE,READ,UPDATE),

FILSTAT=(ENABLED,OPENED)


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File Handling in Programs

Files should not be defined in the Program.

Program should not open or close a File.

Records can be written in any order. A number of records can be

added at a time.

Records can be inserted, updated or deleted.


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Important Key-Words

Dataset/File :- Name in the FCT.

Into/From (WS-Rec) :- Working-Storage Area defined in theprogram where the CICS Puts/Gets the Data.

RIDFLD :- Contains the Record Key.

RESP :- Contains the return code of the executed

command.

LENGTH :- Length of the Record to be Retrieved or Written.


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Random READ

EXEC CICS READ File(filename)

[SET() | Into()]

RIdfld(Rec-Key)

END-EXEC.

Condition: DISABLED, NOTOPEN, NOTFND, LENGERR,DUPKEY, IOERR.


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Example for Random Read

EXEC CICS READ

File( 'INVMAS ')

Into(WS-INVMAS-REC)

Length(WS-INVMAS-LEN)

RIdfld('7135950602') |RIdfld(WS-INVMAS-KEY)

END-EXEC.


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Sequential Read

Sequential Read is done by Browse Oper.

Establish the pointer to the First Record to be Read UsingStartBr.

Next and Previous Records can be Read as required UsingReadNext and ReadPrev.

End the Browse Operation at last.

Browse can be re-positioned.

During Browse Operation, Records cannot be Updated.


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Syntax for STARTBR

EXEC CICS STARTBR

FILE(filename)

RIDFLD(data-area)

END-EXEC.

Condition : DISABLED, IOERR, NOTFND, NOTOPEN.

R di th R d ft


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Reading the Record afterSTARTBR

Sequentially the Next or Previous Record can be read by aREADNEXT or READPREV.

The first READNEXT or READPREV will read the Recordwhere the STARTBR has positioned the File Pointer.


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Syntax of READNext/READPrev

EXEC CICS READNext | READPrev

FILE(name)

INTO(data-area)|SET(ptr-ref)

RIDFLD(data-area)

END-EXEC.

Condition : DUPKEY, ENDFILE, IOERR, LENGERR, NOTFND.


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ENDBRowse

ENDBRowse terminates a Previously issued STARTBR.

SYNTAX :

EXEC CICS ENDBRFILE(filename)

END-EXEC.

Condition: INVREQ


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RESETBR

Its effect is the same as ENDBR and then giving anotherSTARTBR.

Syntax :

EXEC CICS RESETBR

FILE(filename)

RIDFLD(data-area)

END-EXEC.

Condition: IOERR, NOTFND.


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WRITE Command

Adds a new record into the File.

For ESDS, RIDFLD is not used but after write execution, RBAvalue is returned and Record will be written at the end of theFile.

For KSDS, RIDFLD should be the Record Key. The record willbe written depending on the Key.

MASSINSERTion must be done in ascending order of theKey.


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Syntax for WRITE

EXEC CICS WRITE

FILE(filename)

FROM(data-area)

RIDFLD(data-area)END-EXEC.

Condition: DISABLED, DUPREC, IOERR, LENGERR,NOSPACE, NOTOPEN.


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REWRITE Command

Updates a Record which is Previously Read with UPDATE

Option.

REWRITE automatically UNLOCKs the Record afterexecution.


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Syntax for REWRITE

EXEC CICS REWRITE

FILE(filename)

FROM(data-area)END-EXEC.

Condition: DUPREC, IOERR, LENGERR, NOSPACE.


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DELETE Command

Deletes a Record from a dataset.

Record can be deleted in two ways,

1. RIDFLD with the full key in it2. The record read with READ with UPDATE will bedeleted.

Multiple Records Delete is possible using Generic Option.


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Syntax of DELETE

EXEC CICS DELETE

FILE(filename)

RIDFLD(data-area) Optional

END-EXEC.

Condition: DISABLED, DUPKEY, IOERR, NOTFND,

NOTOPEN.


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General Exceptions

The following exceptions usually will occur forALL CICS filehandling commands.

FILENOTFOUND,

NOTAUTH,

SYSIDERR,

INVREQ


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CICS Error HandlingProcedures


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Error Handling in CICS

Possible Errors:

Conditions that aren't normal from CICS's point of view but

that are expected in the program.

Conditions caused by user errors and input data errors.

Conditions caused by omissions or errors in the application

code.

Errors caused by mismatches between applications and

CICS tables, generation parameters and JCL

Errors related to hardware or other system conditions beyond

the control of an application program.


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Error Handling methods

When the error (exceptional conditions) occur, the program can

do any of the following

Take no action & let the program continue - Control returns to

the next inst. following the command that has failed to execute.A return code is set in EIBRESP and EIBRCODE. This state

occurs cause of NO HANDLE /RESP/IGNORE conditions

Pass control to a specified label - Control goes to a label in the

program defined earlier by a HANDLE CONDITION command.

Rely on the system default action - System will terminate or

suspend the task depends on the exceptional condition occurred

Error Handling methods


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Error Handling methods(Contd..)

HANDLE CONDITION condition[(label)]... 'condition' specifiesthe name of the condition, and 'label' specifies the locationwithin the program to be branched

Remains active while the program is executing or until itencounters IGNORE/another HANDLE condition.

Syntax :EXEC CICS HANDLE CONDITION ERROR(ERRHANDL)

LENGERR(LENGRTN)

END-EXECThis example handles DUPREC condition separately, all theother Errors together. LENGERR will be handled by system


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HANDLE Condition

Example of Handle condition:

EXEC CICS HANDLE CONDITION

NOTFND(RECORD-NOT-FOUND)

END-EXEC

This condition catches the NOTFND condition and transfers control to the

REC-NOT- FOUND paragraph in the program. The error handling logic can be

coded in the REC-NOT-FND paragraph.


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Alternative to Handle condition

NOHANDLE to specify no action to be taken for any condition orattention identifier (AID)

RESP(xxx) "xxx" is a user-defined full word binary data area. Onreturn from the command, it contains a return code. Later, it canbe tested by means of DFHRESP as follows,

If xxx=DFHRESP(NOSPACE) ... or

If xxx=DFHRESP(NORMAL) ...


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IGNORE Condition

IGNORE CONDITION condition ...

condition specifies the name of the condition that is to beignored( no action will be taken)

Syntax :

EXECCICS IGNORE CONDITION

ITEMERR

LENGERR

END-EXEC This command will not take any actions if the given two error

occurs and will pass the control to the next instruction

Sample program to use Handle


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Sample program to use Handlecondition

Here is an example of the CICS- COBOL code with properhandling of errors

Procedure Division.EXEC CICS HANDLE CONDITION

NOT-FND(REC-NOT-FOUND)END EXEC.

:

EXEC CICS READ

DATASET(SAMPLE)

RIDFLD(EMP-NO)

INTO (EMP-REC)

END-EXEC

:

GO TO LAST-PART

Sample program to use Handle


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Sample program to use Handlecondition (Contd..)

REC-NOT-FOUND

MOVE NOT-ON-FILE TO NAMEO ( SYMBOLIC MAP

PARAMETER)

LAST-PART.

EXEC CICS SEND

MAP (TC0BM31)

MAPSET(TC0BM30)

FROM (TC0BM310)

DATA-ONLY

END-EXEC


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PUSH & POP

To suspend all current HANDLE CONDITION, IGNORECONDITION, HANDLE AID and HANDLE ABEND commands.

Used for eg. while calling sub-pgms (CALL).

While receiving the control, a sub-program can suspend Handlecommands of the called program using PUSH HANDLE.

While returning the control, it can restore the Handle commandusing POP HANDLE.


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Syntax of Push & Pop

Syntax of Push :

EXEC CICS Push

Handle

END-EXEC.

Syntax of Pop :

EXEC CICS PopHandle

END-EXEC.


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EXEC Interface Block (EIB)

CICS provides some system-related information to each task asEXEC Interface Block (EIB)

Unique to the CICS command level

EIBAID Attention- Id (1 Byte)

EIBCALEN Length of DFHCOMMAREA (S9(4) comp)EIBDATE Date when this task started (S9(7) comp-3)

EIBFN Function Code of the last command ( 2Bytes)

EIBRCODE Response Code of the last command (6

Bytes)EIBTASKN Task number of this task (S9(7) comp-3)

EIBTIME Time when this task started (S9(7) comp-3)

EIBTRMID Terminal-Id (1 to 4 chars)

EIBTRNID Transaction-Id (1 to 4 chars)


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PCT Entry

DFHPCT TYPE=ENTRY

TRANSID= name

PROGRAM=name

TASKREQ=pf6

RESTART=yes/no ( TRANSEC = 1 to 64)

RSLKEY= 1 to 24 resource level key

SCTYKEY= 1 to 64 security key

:

:other options


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PROGRAM CONTROL


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Program Control Commands

LINK

XCTL

RETURN

LOAD

RELEASE


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LINK

Used to pass control from one application program to another

The calling program expects control to be returned to it

Data can be passed to the called program using COMMAREA

If the called program is not already in main storage it is loaded

INK S


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LINK Syntax

EXEC CICS LINK

PROGRAM(name)

[COMMAREA(data-area)

[LENGTH(data-value)]]

END-EXEC.

Conditions : PGMIDERR, NOTAUTH, LENGERR

XCTL


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XCTL

To transfer control from one application program to another in

the same logical level

The program from which control is transferred is released

Data can be passed to the called program using COMMAREA If the called program is not already in main storage it is loaded

XCTL S t


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XCTL Syntax

EXEC CICS XCTL

PROGRAM(name)


[LENGTH(data-value)]]

END-EXEC.

Conditions : PGMIDERR, NOTAUTH, LENGERR

RETURN


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RETURN

To return control from one application program to another at a

higher logical level or to CICS

Data can be passed using COMMAREA when returning to CICS

to the next task

RETURN S t


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RETURN Syntax

EXEC CICS RETURN

[TRANSID(name)


[LENGTH(data-value)]]]

END-EXEC.

Conditions : INVREQ, LENGERR

CICS Level 0


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PROG A

LINK

RETURN

PROG BXCTL

PROG CLINK

RETURN

PROG D

XCTLPROG E

RETURN

Level 1

Level 2

Level 3

Application Program

Logic Levels

LOAD


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LOAD

To load program/table/map from the CICS DFHRPL concatenationlibrary into the main storage

Using load reduces system overhead

Syntax :

EXEC CICS Load

Program(name)

[SET (pointer-ref)]

[LENGTH (data-area)]END-EXEC.

Condition : NOTAUTH, PGMIDER

RELEASE


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RELEASE

To RELEASE a loaded program/table/map

Syntax :

EXEC CICS RELEASEPROGRAM(name)

END-EXEC.

Conditions : PGMIDERR, NOTAUTH, INVREQ

COMMAREA


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COMMAREA

Data passed to called program using COMMAREA in LINK andXCTL

Calling program - Working Storage definition

Called program - Linkage section definition under

DFHCOMMAREA Called program can alter data and this will automatically

available in calling program after the RETURN command

( need not use COMMAREA option in the return for thispurpose )

EIBCALEN is set when COMMAREA is passed


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Communication WithDatabases

CICS DB2


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CICS - DB2

CICS provides interface to DB2.

DB2 requires CICS Attachment Facility to connect itself toCICS

CICS programs can issue commands for SQL services in order

to access the DB2 database.

EXEC SQL function

[options]

END-EXEC

Operating system


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CICS REGION DB2 REGION

App. Pgm. EXEC SQL.. CICS Attachment Facility

DB2

Database

DB2 Database access by CICS

RCT Entry


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RCT Entry

The CICS-to-DB2 connection is defined by creating andassembling the resource control table (RCT)

The information in RCT is used to control the interactionsbetween CICS & DB2 resources

DB2 attachment facility provides a macro (DSNCRCT) togenerate the RCT.

The RCT must be link-edited into a library that is accessible toMVS


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QUEUES

Transient data Control


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Transient data Control

Provides application programmer with a queuing facility

Data can be stored/queued for subsequent internal or externalprocessing

Stored data can be routed to symbolic destinations

TDQs require a DCT entry Identified by Destination id - 1 to 4 bytes

TDQs


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TDQs

Intra-partitioned - association within the same CICS subsystem

Typical uses are

- ATI (Automatic Task Initiation) associated with trigger level

- Message switching

- Broadcasting etc

Extra-partitioned - association external to the CICS subsystem, Canassociate with any sequential device - Tape, DASD, Printer etc

Typical uses are- Logging data, statistics, transaction error messages

- Create files for subsequent processing by Non-CICS / Batch

programs.

TDQs


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TDQs

Operations

Write data to a transient data queue (WRITEQ TD)

Read data from a transient data queue (READQ TD)

Delete an intra partition transient data queue (DELETEQ TD).

WRITEQ TD


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WRITEQ TD

Syntax :

EXEC CICS WRITEQ TD

QUEUE(name)

FROM(data-area)

[LENGTH(data-value)]

[SYSID(systemname)]

END-EXEC.

Conditions: DISABLED, INVREQ, IOERR, ISCINVREQ,LENGERR, NOSPACE, NOTAUTH, NOTOPEN, QIDERR,SYSIDERR

READQ TD


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READQ TD

Reads the queue destructively - Data record not available in thequeue after the read.

Syntax :

EXEC CICS READQ TD

QUEUE(name)

{INTO(data-area) | SET(ptr-ref) }


[NOSUSPEND]

END-EXEC.Conditions : DISABLED, IOERR, INVREQ, ISCINVREQ,LENGERR, NOTAUTH, NOTOPEN, QBUSY, QIDERR, QZERO,SYSIDERR

DELETEQ TD


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DELETEQ TD

Deletes all entries in the queue

Syntax :

EXEC CICS DELETEQ TD

QUEUE(name)

END-EXEC.

Conditions: INVREQ, ISCINVREQ, NOTAUTH,QIDERR, SYSIDERR

Destination Control Table


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Destination Control Table

DCT is to register the information of all TDQs

Destination Control Program (DCP) uses DCT to identify allTDQs and perform all I/O operations.

DFHDCT is a macro to define intra & extra partition TDQs

TYPE=INTRA/EXTRA REUSE option specified along with intra partition TDQ tells

whether the space used by TDQ record will be removed &reused after it has been read.

Automatic Task Initiation


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Automatic Task Initiation

Facility through which a CICS transaction can be initiatedautomatically

DFHDCT TYPE=INTRA

DESTID=MSGS

TRANSID=MSW1TRIGLEV=500

When the number of TDQ records reaches 500, the

transaction MSW1 will be initiated automatically

ApplicationsMessage switching & Report printing

Temporary Storage Control


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Temporary Storage Control

Provides application programmer the ability to store and retrievedata in a TSQ

Application can use the TSQ like a scratch pad

TSQs are

- Created and deleted dynamically- No CICS table entry required if recovery not required

- Identified by Queue id - 1 to 8 bytes

- Typically a combination of termid/tranid/operid

Each record in TSQ identified by relative position, called the itemnumber


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TSQs - Typical uses


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TSQs Typical uses

Data passing among transactions

Terminal Paging

Report printing

WRITEQ TS


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WRITEQ TS

Syntax :

EXEC CICS WRITEQ TS

QUEUE(name)

FROM(data-area)


[NUMITEMS(data-area) |

ITEM(data-area) [REWRITE] ]

[MAIN|AUXILIARY]

[NOSUSPEND]END-EXEC.

Conditions : ITEMERR, LENGERR, QIDERR, NOSPACE, NOTAUTH,SYSIDERR, IOERR, INVREQ, ISCINVREQ

READQ TS


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READQ TS

Syntax :

EXEC CICS READQ TS

QUEUE(name)

{INTO(data-area) | SET(ptr-ref) }

LENGTH(data-value)

[NUMITEMS(data-area)]

[ITEM(data-area) | NEXT ]

END-EXEC.

Conditions : ITEMERR, LENGERR, QIDERR, NOTAUTH,SYSIDERR, IOERR, INVREQ, ISCINVREQ

DELETEQ TS


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DELETEQ TS

Deletes all entries in the queue

Syntax :

EXEC CICS DELETEQ TS

QUEUE(name)

END-EXEC.

Conditions: INVREQ, ISCINVREQ, NOTAUTH, QIDERR,SYSIDERR


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INTERVAL & TASKCONTROL

ASKTIME


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ASKTIME

Used to obtain current date and time

Syntax :

EXEC CICS ASKTIME[ABSTIME(data-area)]

END-EXEC.

EIBDATE and EIBTIME updated with current date and time

ABSTIME returns value of time in packed decimal format

FORMATTIME


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FORMATTIME

Syntax :

EXEC CICS FORMATTIME ABSTIME(data-ref)

[YYDDD(data-area)]

[YYMMDD(data-area)]... etc.

[DATE(data-area) [DATEFORM[(data-area)]]]

[DATESEP[(data-value)]]

[DAYOFMONTH(data-area)]

[MONTHOFYEAR(data-area)]

[YEAR(data-area)].....[TIME(data-area) [TIMESEP[(data-value)]]]

END-EXEC.

Condition: INVREQ

DELAY


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DELAY

Used to DELAY the processing of a task

The issuing task is suspended for a specified interval or Until thespecified time

Syntax :

EXEC CICS DELAYINTERVAL(hhmmss) | TIME(hhmmss)

END-EXEC

Conditions: EXPIRED, INVREQ

START


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S

Used to start a transaction at the specified terminal and at thespecified time or interval

Data can be passed to the new transaction

Syntax :

EXEC CICS START TRANSID(transid)

[TERMID(termid)

TIME(hhmmss) | INTERVAL(hhmmss) ]

END-EXEC

Conditions : INVREQ, LENGERR,TERMIDERR, TRANSIDERR

Other Interval ControlC d


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Commands

POST - to request notification when the specified time hasexpired.

WAIT EVENT - to wait for an event to occur.

RETRIEVE - Used to retrieve the data passed by the START

CANCEL -Used to cancel the Interval Control requests. eg.DELAY,POST and START identified by REQID.

SUSPEND - Used to suspend a task

ENQ - to gain exclusive control over a resource

DNQ - to free the exclusive control from the resource gained byENQ


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Recovery & Restart

The Need for Recovery/Restart


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y

The possible failures that can occur outside the CICS system are

Communication failures (in online systems)

Data set or database failures

Application or system program failures

Processor failures & Power supply failures.

Recovery/Restart facilities are required to minimize or if possible,eliminate the damage done to the online system, in case of the

above failures to maintain the system & data integrity.

RECOVERY


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An attempt to come back to where the CICS system or thetransaction was when the failure occurred

Recoverable Resources

VSAM filesIntrapartition TDQ

TSQ in the auxiliary storage

DATA tables

Resource definitions & System definition files

RESTART


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To resume the operation of the CICS system or the transaction whenthe recovery is completed

Facilities for Recovery/Restart


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y

Facilities for CICS Recovery/Restart

Dynamic Transaction Backout

Automatic Transaction Restart

Resource Recovery Using System Log

Resource Recovery Using Journal

System Restart

Extended Recovery Facility (XRF)

Dynamic Transaction Backout(DTB)


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(DTB)

When the transaction fails, backing out the changes made bythe transaction while the rest of the CICS system continuesnormally is called DTB

CICS automatically writes the before image information of therecord into the dynamic log for the duration of one LUW ,thework between the two consecutive SYNC points

When an ABEND occurs, CICS automatically recovers all

recoverable resources using the info. in dynamic log (SetDTB=YES in PCT)

LUW & SYNC point


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p

The period between the start of a particular set of changes andthe point at which they are complete is called a logical unit ofwork - LUW

The end of a logical unit of work is indicated to CICS by a

synchronization point (sync pt). Intermediate SYNC pt. can be done by

Syntax :

EXEC CICS SYNCPOINT

[ROLLBACK]

END-EXEC

LUWs & SYNC pts


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p

|- - - - - - - - - - - - LUW - - - - - - - - - |

Task A|---------------------------------------------|

SOT EOT-SP

|- - - LUW- - |- - - LUW- - |- - -LUW- - |

Task B|---------------->--------------->--------------|

SOT SP SP EOT-SP

When the failure occurs, changes made within the abendingLUW will be backed out.

Automatic Transaction Restart


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CICS capability to automatically restart a transaction after allresources are recovered through DTB

If the transaction requires automatic restart facility, set

RESTART=YES in PCT

Care should be taken in order to restart the task at the pointwhere DTB completes in the case of intermediate SYNC point


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Program Preparation

Introduction


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Preparing a Program to run in CICS Environment.

Defining the Program in the CICS Region.

Executing the Program.

Program preparation


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LOADMODULE

LINKEDIT

COBOL

COMPILER

CICS

COMPILER

DB2

PRECOMPILER

IF DB2 :

SOURCE

Program preparation

Preparing a Program


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CICS requires the following steps to prepare a program

Translating the Program.

Assemble or Compile the Translator Output. &

Link the Program.

Translation


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Translates the EXEC CICS Statements into the Statementsyour Language (COBOL) Compiler can Understand.

The Translator gives two outputs, a Program Listing asSYSPRINT and a Translated Source in SYSPUNCH.

The SYSPUNCH is given as the input to the Program Compiler. If any Copy Books are used in the Program, there should not be

any CICS Statements in the Copy Book.

Compiling or Linking


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As the CICS Commands have been translated, the compilationof the CICS program is the same as language program.

Hence, the compiler options can be specified as required.

Defining the Program


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The Application should be defined and installed into the PPT.

This can be done either by using CEDA trans or DFHPPT.


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CICS Supplied Transactions

CESN/CESF Transactions


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To sign on to CICS system

CESN [USERID=userid] [,PS=password][,NEWPS=newpassword][,LANGUAGE=l]

Userid & password values can be from 1-8 chars.

In RACF, the Userid given in CESN is verified. NEWPS to change the password and LANGUAGE to choose

national language

Sign off by CESF which breaks the connection between the userand CICS

If the Sign on is done twice for the same userid at the terminal,the previous operator will be signed off

CECI - Command LevelInterpreter


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Interpreter

To build and test the effect of EXEC CICS commands

CECI ASSIGN is used to get the current userid,sysid, terminal id,application id etc..

Before using the maps in programs, it can be tested using CECI

to check how it appears on the screen. CECI gives the complete command syntax of the specified

command.

CECI READQ TD QUEUE(TESTL001) will read the currentrecord of the given TDQ

CEMT-Master TerminalTransaction


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Transaction

CEMT provides the following services

Displays the status of CICS & system resources

Alter the status of CICS & system resources Remove the installed resource definitions

Perform few functions that are not related to resources

CEDF-Execution DiagnosticFacility


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Facility

To test command level application programs interactively

CEDF [termid/sysid/sessionid] [,ON/,OFF]

Termid - the identifier of the terminal on which the transaction tobe tested is being run

Sessionid - To test/monitor a transaction attached across anMRO/ISC session

Sysid - To test a transaction across an APPC session

CEDF (Contd..)


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The points at which EDF interrupts execution of the program andsends a display to the terminal

At transaction initialization, after EIB has been initialized andbefore the app. pgm given control

Start of execution of each CICS command (auguement

values can be changed at this point) End of execution of each CICS command and before the

Handle condition mechanism is invoked (response codevalues can be changed)

At program termination & at normal task termination

When an ABEND occurs & at abnormal task termination. EIB values can be changed..& CEBR can be invoked

CEBR-Temporary StorageBrowse


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Browse

To browse the contents of CICS temporary storage queues(TSQ)

CEBR by default will show the queue associated with the currentterminal CEBRL001 which can be overridden to view any otherqueue

TERM to browse TSQ for another terminal

QUEUE to make the named queue, current

PUT to copy the current queue contents into TDQ

GET to fetch TDQ for browsing

PURGE erases the contents of the current queue

Exercise - 2


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Exercise 2

Exercise - 2


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Th k Y

cics mainframes

Documents