//MYJOB JOB(E343),'ABCDEFGH' //JOBLIB DD DSN=ABCD.PROD.LOADLIB,DISP=SHR //STEP1 EXEC PGM=PROG //STEPLIB DD DSN=ABCD.PPROD.LOADLIB,DISP=SHR //STEP2 EXEC PGM=PROG1 //STEPLIB DD DSN=ABCD.TEST.LOADLIB,DISP=SHR ..... ..... In the above code, from which library the loadmodule of PROG1 is executed

In JCL, STEPLIB DD statements override JOBLIB for the specific step where they are defined. For STEP2 executing PROG1, the STEPLIB DD statement in STEP2 specifies ABCD.TEST.LOADLIB, which takes precedence over the JOBLIB at the job level. The JOBLIB (ABCD.PROD.LOADLIB) would be used only if STEPLIB was not defined in STEP2, and the earlier STEPLIB in STEP1 only applies to that step, not subsequent steps.