On Sat, 23 Dec 2023 15:54:38 +0000, Peter Relson <rel...@us.ibm.com> wrote:
>I view their being two main reasons for recovery (and not necessarily in the >order I show): Everyone ignores the third main reason which is stopping abends from becoming catastrophic. IBM knows this is ignored and plans accordingly. IBM uses multiple techniques that are not obvious. For instance, consider how IBM handles the most dangerous z/OS user exit which is the last one anyone thinks. It's not allocation, job, interpreter nor any other exits that people think. It's the message user exit. To stop people from doing something dumb, IBM requires a user exit for a specific message id (see SETPROG). IBM knows a single message user exit would invite catastrophic situations because it's far too complicated and most people won't understand the recovery requirements. You can code specific IOS, JES, z/OS and more message exits but the concept is that recovery only affects a small portion of the system. IBM allows messages thru the SSI but few people venture onto the SSI because of the complexity. The expectation is that anyone using the SSI will use advanced techniques for messages that can be issued from almost any environment. SSI programmers must understand how and when to handle locks, FRR, ESTAE, running disabled and everything else that can affect SSI code. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
