Conventions for Return to Caller for an IPCS Exit Routine
z/OS MVS IPCS Customization
SA23-1383-00
For IPCS and ABEND/SNAP Formatting
All
exit routines must return control to their calling routine using standard
linkage. Register 15 contains a return code that is used by some
of the IPCS functions that call exit routines. Return code conventions
differ from one type of exit routine to another and are discussed
as part of the “Output” topic for each type of exit routine.