Also, the question is somewhat unanswerable without knowing the environment.
z/OS? VSE? CMS? Non-privileged program? Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of Charles Mills Sent: Saturday, March 5, 2022 7:40 AM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: Testing address validity I think VSMLOC may do the job for you. But all it can tell you is that the storage is allocated at the time of the VSMLOC, not what it might be a microsecond later when you access it. THE BEST thing is to set up an ESPIE and recover from any S0C4. ESPIE is lightweight. This is exactly what it is intended for. (Or SETFRR if more appropriate to your environment.) Really an IBMMAIN question. Not really about the assembler language. Charles -----Original Message----- From: IBM Mainframe Assembler List [mailto:ASSEMBLER-LIST@LISTSERV.UGA.EDU] On Behalf Of João Reginato Sent: Saturday, March 5, 2022 4:45 AM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Testing address validity Importance: Low Hi Which is the best instruction to test if a virtual address is still valid to avoid an unexpected S0C4?