Batch processing and JCL

What batch is

Batch processing runs a program once on a whole file, without a user waiting. Payroll, statements, and end-of-day totals are batch jobs: they read input files, process every record, and write reports.

JCL basics

On z/OS, Job Control Language describes the job: which program to run, which files to use, and what to do with the output. The COBOL program itself is unchanged; JCL maps its DD names to real files:

//PAYROLL JOB CLASS=A //STEP1 EXEC PGM=PAYROLL //EMPFILE DD DSN=PAY.EMP.IN,DISP=SHR //REPORT DD SYSOUT=*

Job steps

One job is a chain of steps: sort first, then the COBOL program, then a report print. The scheduler runs the chain nightly, and RETURN-CODE from each step decides whether the next step may start.

Next: File status and transactions

Article author: Arthur Isaev