Cob Basics

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TITLE : Introduction to COBOL

Purpose:

To provide introduction to COBOL Language.

To provide context where its uses might be understood.

To provide an introduction to the major characteristicsof a COBOL program

OBJECTIVES:

To be aware of the significance of COBOL and its

divisions

To be aware of COBOL coding rules

How to run a COBOL program in MVS environment

Unit1


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What is COBOL

The word COBOLis an acronym that stands forCOmmon Business Oriented Language

COBOL is a high-level programming language first developed

by the CODASYL Committee (COnference on Data SYstemsLanguages) in 1960

Three ANSI standards for COBOL have been produced: in1968, 1974 and 1985.

A new COBOL standard introducing object-orientedprogramming to COBOL, is due within the next few years

Designed for business oriented applications


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Significance of COBOL

For over four decades COBOL has been the dominantprogramming language in the business computing domain

In 1997 they estimated that there were about 300 billion lines

of computer code in use in the world. Of that they estimatedthat about 80% (240 billion lines) were in COBOL and 20%

(60 billion lines) were written in all the other computer

languages combined

2004-2005 15% of all new applications (5 billion lines) will be

developed in COBOL while 80% of alldeployed applications

will include extensions to existing legacy (usually COBOL)

programs.


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Significance of COBOL

COBOL applications often run in critical areas of business.For instance, over 95% of financeinsurance data is processedwith COBOL

COBOL applications often deal with enormous volumes of

data. Single production files and databases measured interabytes are not uncommon.

COBOL contains such English-like structural elements asverbs, clauses, sentences, sections and divisions.

COBOL is a simple language

COBOL has a 30 year proven track record for applicationmaintenance, enhancement and production support at theenterprise level.


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Anatomy of COBOL Program

Divisions

Sections

Paragraphs

Sentences

Statements


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DivisionsA division is a block of code, usually containing one or moresections, that starts where the division name is encounteredand ends with the beginning of the next division

SectionsA section is a block of code usually containing one or more

paragraphs. A section begins with the section name and endswhere the next section name is encountered. A section name is

followed by the word SECTION


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ParagraphsA paragraph is a block of code made up of one or moresentences. A paragraph begins with the paragraph name andends with the next paragraph or section name

Sentences

A sentence consists of one or more statements and isterminated by a period.

StatementsA statement consists of a COBOL verb


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COBOL coding rules

Traditionally, COBOL programs were written on coding formsand then punched on to punch cards

The first six character positions are reserved for sequencenumbers.

Column 7 is used for special purpose

An entire line can be designated as comment by placing a *

While printing, Source listing can be ejected to a new pageby placing a /

Used for continuation of non numeric literals

Columns 8-72 are used to write the coding instructions

Columns 73-80 are used for identification


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COBOL coding rules

Columns 8-11 is called Area A or Margin A

Columns 12-72 is called Area B or Margin B

Entries of Area A should start between the columns 8-11 andcan extend to Area B

Entries of Area B should start between columns 12-72

All division names, section names, paragraph names, FDentries and 01 level numbers must start in Area A.

All other sentences must start in Area B.


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COBOL Divisions

The IDENTIFICATION DIVISION supplies informationabout the program to the programmer and the compiler

The ENVIRONMENT DIVISION is used to describe theenvironment in which the program will run.

The DATA DIVISION provides descriptions of the data-itemsprocessed by the program

The PROCEDURE DIVISION contains the code used tomanipulate the data described in the DATA DIVISION. It ishere that the programmer describes his algorithm


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How to Run COBOL program in MVS

Compile the program using JCL (Job Control Language)

Generate the Load module with the help of Bind JCL

Run the program using Exec statement in JCL.


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Sample JCL

//IGYWC PROC LNGPRFX='IGY.V2R2M0',SYSLBLK=3200

//*

//*COMPILE A COBOL PROGRAM

//*

//*PARAMETER DEFAULT VALUE USAGE

//*SYSLBLK 3200 BLKSIZE FOR OBJECT DATA SET//*LNGPRFXIGY.V2R2M0 PREFIX FOR LANGUAGE DATA SET

NAMES

//*

//*CALLER MUST SUPPLY //COBOL.SYSIN DD ...

//*//COBOL EXEC PGM=IGYCRCTL,REGION=2048K

//STEPLIB DD DSNAME=&LNGPRFX..SIGYCOMP,

//DISP=SHR

//SYSPRINT DD SYSOUT=*

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