In OS/VS COBOL, if a COBOL library subroutine detects a serious error at execution time (for example, a SYSOUT DD statement is missing), ILBOSRV1 sets the return code and the JOB STEP COMPLETION/ CONDITION CODE to 12 (CC12) upon terminating the run unit. A return code of 12 is compatible with versions 2 and 3 of American National Standard COBOL.

If you want to change the default return code, you can overlay the halfword X'000c' at displacement X'0002' into CSECT ILBOSRV with the error completion code of your choice. If the halfword is set to a NEGATIVE value during STOP RUN or GOBACK processing, the program is terminated with the USER ABEND 0295 (ABENDU0295) instead of a return code 12.

Because some users might depend on programs abending in the preceding conditions, you can apply the superzap as a user modification (IGZWZA2) to force a USER ABEND 0295.