If you haven't changed the data or conceivably the environment, retrying the instruction will get the same result. That shouldn't be a surprise. If you were to try, you'd likely have to decipher the instruction so that you could figure out what data and/or regs it was using and make sure to change something for "the next time".
I believe long ago it used to be the case that the PL/I compiler (this was before "C" was anything more than the 3rd letter of the alphabet), would get control for a page fault or segment fault on data that it knew about, set up the data so that a retry of the instruction would work, and do so. Thinking about this now, we have no idea how it could do that in a predictable way (since it would get control for "normal" page faults too). Of course, the architecture accommodates and allows retrying the instruction. That is used by the system when (for example) a page fault occurs. The system stops the work unit, asynchronously pages in the page (when the page actually was valid but paged out) and resets the work unit to re-execute the instruction. And the program old PSW's instruction address for a page fault doesn't even need to be backed up to get to the right place to re-execute. Peter Relson z/OS Core Technology Design ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
