My very first oh-dark-thirty support call as a sysprog was for a program I had just updated. I had cluelessly assembled it using JCL that had RENT,REFR in the link edit step. After testing, I moved it from the non-APF test library to the APF production library. Big S0C4.
All inadvertent. A set of lessons I have never forgotten. . . J.O.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 323-715-0595 Mobile 626-543-6132 Office ⇐=== NEW [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Peter Relson Sent: Sunday, July 15, 2018 5:55 PM To: [email protected] Subject: (External):Re: Linklist and APF <snip> There's also REFRPROT nowadays. But that should have never been needed as an option; it should have been the universal behaior ab ovo. How much extra would it have cost to load user programs as well as system programs into write-protected storage? </snip> Page protection did not exist at the time that this logic was introduced. So "ab ovo" was not possible if used the way I interpret it. Changing the behavior when page protection was added would be viewed, properly, as incompatible and thus unacceptable. And the extra storage utilization (page multiple on page boundary) might have been felt to be unacceptable too (perhaps no longer). Users are creative and might have chosen to rely on the existing documented behavior. It is also well known that the system does not "protect" against reentrant programs writing into themselves, just makes it harder. And it is also well known that a program could write into itself and still be reentrant (although that is surely frowned upon these days). Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
