I *think* the latter. I seem to recall that exits don't get re-entered. Not an expert.
Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of John McKown Sent: Friday, November 29, 2013 4:58 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Curiosity: ETXR exit code (ATTACHX macro) Suppose that I have a program which is heavily multitasking. There is the parent task and multiple subtasks, all direct children of the single parent. The ATTACHX macro uses the ETXR parameter, which specifies a single routine which does housekeeping of some sort. Also assume that the subtasks are being created and ending "randomly". That is the main task is "doing its thing", then a subtask ends and drives the ETXR code under the parent TCB (I think under an IRB). Now this can happen anywhere in the parent's "main loop", so I know that I need to serialize properly between the "main loop" code and the ETXR code. Assume that I have done so. I am wondering if a second child terminates while the parent TCB is in the ETXR code for a child, will the ETXR code be interrupted and "redriven" for the newly terminating child TCB. Or does RTM itself serialize the ETXR code so that a second instance is not driven until the first instance finishes (by exiting, thus going back to the parent's "main loop"). I.e. can the RB chain at some point look like: PRB of parent, IRB of ETXR #1, IRB of ETXR #2, IRB of ETXR #3 for a time line like: main TCB loop running child #1 ends, ETXR#1 starts running on main TCB child #2 ends, ETXR#2 starts running on main TCB (EXTR#1 interrupted) ETXR#2 ends, ETXR#1 resumes where it left off ETXR#1 ends, main TCB code loop resumes from where it was interrupted. or is the second ETXR "deferred" until the previous invocation does an SVC 3 to return to the main routine. Timeline like: main TCB loop child ends, causing ETXR to be invoked on main TCB child ends while ETXR active, is queued ETXR #1 ends queued ETXR starts execution ETXR #2 ends main TCB loop resumes I think the former. with ETXR#2 interrupting ETXR#1 is what really happens. I can't think of a way, off hand to test this. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
