CICS-Enabled COBOL Program

A CICS-enabled COBOL program is an ordinary COBOL program that contains CICS commands and follows CICS rules. This page explains what makes a program CICS-enabled and the rules every such program must follow.

What makes a program CICS-enabled

• The program contains at least one EXEC CICS command in its Procedure Division.
• The source is passed through the CICS translator before the COBOL compiler sees it.
• The translator inserts the DFHEIBLK (EIB) and DFHCOMMAREA definitions into the Linkage Section automatically.
• The program is defined in the PPT and is started through a transaction id defined in the PCT.

Rules a CICS program must follow

• End the program with EXEC CICS RETURN. Never use STOP RUN under CICS.
• Do not use DISPLAY or ACCEPT for terminal I/O. Use EXEC CICS SEND and RECEIVE.
• Do not use COBOL file verbs (READ, WRITE, REWRITE, DELETE) or OPEN/CLOSE. Use the EXEC CICS file commands.
• Write quasi-reentrant code: the same load module can serve many tasks at once, so do not depend on values left by another task.
• Do not use the COBOL SORT verb or other statements that need batch-only services unless your shop supports them.

Minimum parts of a CICS program

• IDENTIFICATION DIVISION with a PROGRAM-ID, like any COBOL program.
• DATA DIVISION with a LINKAGE SECTION that declares DFHEIBLK and DFHCOMMAREA.
• PROCEDURE DIVISION with your logic, EXEC CICS commands, and a final EXEC CICS RETURN.
• The example below is the smallest working pattern. The translator generates DFHEIBLK for you, so you only declare DFHCOMMAREA yourself.