Overrides In JCL

1. REGION Parameter - JOB Over-rides EXEC

//JOB1 JOB (A123),'XYZ'
//        REGION=40K   
//STEP1 EXEC PGM=PGM1,REGION=10K
//STEP2 EXEC PGM=PGM2,REGION=20K

Example : If STEP1 utilises complete 10K,also STEP2 utilises 20K but require more region , it over-rides its step region declaration and utilises the job region declaration (Provided there is no region requirement from any other step).
But if it exceeds the JOB region declaration, the job abebds.

2.TIME Parameter - EXEC Over-rides JOB

//JOB1 JOB (A123),'XYZ'
//        TIME=12
//STEP1 EXEC PGM=PGM1,TIME=04
//STEP2 EXEC PGM=PGM2,TIME=04
//STEP3 EXEC PGM=PGM3,TIME=02

Example : If STEP1 or STEP2 utilises more than 4 minutes,then even though total time for job is 12 minutes, the steps are not executed and the job abends.
If JOB is coded smaller time than the EXEC, then the JOB will terminateto the specified time of the JOB.

3. COND Paramter - JOB Over-rides EXEC

4. JOBLIB AND STEPLIB Parameters - STEPLLIB over-rides JOBLIB