As it stands right now during a shutdown hang, TCSACTN=FORCE will not close down LU6.2 parallel connections until after CNOS close processing has completed. Once a region begins to shutdown and gets to the process of terminating of VTAM sessions, if a partner LU6.2 connection is hung and cannot respond to CNOS close processing, then the region shutting down will hang. The region that is shutting down will hang indefinitely until it is either cancelled or the partner LU6.2 connection responds to the CNOS processing. Even after the regions TCSWAIT sit parameter expires, TCSACTN=FORCE will not force close the partner LU6.2 connection that is not responding. We believe that this will lead to a lot of shutdown hang problems that we have already begun to see.
We believe that TCSACTN=FORCE should terminate partner LU6.2 connections even if CNOS close processing has not completed. In the same shutdown hang scenario, we believe that after the regions TCSWAIT sit parameter expires, TCSACTN=FORCE should kick in and force close the partner LU6.2 connection that has not responded. This would be useful because it would avoid a lot of shutdown hang problems where a partner LU6.2 connection has not responded to CNOS close processing. This will benefit customers so they will not have to manually cancel their CICS regions when they are hung at shutdown in this scenario.
*NOTE*: Our CICS shutdown assist transaction CESD does not help in this scenario. After all non-system tasks have been succuessfully terminated during shutdown, CESD believes that its job is done and does not help with any hangs while terminating VTAM sessions.
You can see below we recreated this problem in our test regions. You can see that we specified TCSWAIT=2 and TCSACTN=FORCE. At 19:15:12 we begin shutdown, and then it starts to hang at 19:15:13 when the termination of VTAM ACBs begins. You can then see that 2 minutes later at 19:17:13 TCSWAIT=2 threshold expires but shutdown continues to hang because TCSACTN=FORCE does not force close the VTAM ACB until CNOS processing has completed. This is where we believe that TCSACTN=FORCE should kick in and automatically close the hung LU6.2 connection so shutdown can proceed. Shutdown will continue to hang until you manually cancel the region or untiil the other region responds back to CNOS processing. You can see at 19:19:52 we had to manually cancel the region or else, in this case, it would have hung forever.
19.14.15 JOB29973 DFHPA1927 IYNXU TCSWAIT=2
19.14.15 JOB29973 DFHPA1927 IYNXU TCSACTN=FORCE
...
19.15.12 JOB29973 +DFHTM1715 IYNXU CICS is being quiesced by userid CICSUSER in transaction CEMT at netname IYCNTC96.
19.15.12 JOB29973 +DFHDM0102I IYNXU CICS is quiescing.
19.15.12 JOB29973 +DFHMN0115I IYNXU CICS Server z/OS WLM Health percentage is now 0.
19.15.12 JOB29973 +DFHCESD IYNXU SHUTDOWN ASSIST TRANSACTION CESD STARTING. SHUTDOWN IS NORMAL.
19.15.12 JOB29973 +DFHEC1006I IYNXU Event processing status is DRAINING.
19.15.12 JOB29973 +DFHEC1006I IYNXU Event processing status is STOPPED.
19.15.12 JOB29973 +DFHTM1782I IYNXU All non-system tasks have been successfully terminated.
19.15.13 JOB29973 +DFHZC2305I IYNXU Termination of VTAM sessions beginning
19.17.13 JOB29973 +DFHZC2352 IYNXU 300
300 22/03/2024 19:17:13 IYNXU UTOT IYNXT Intersystem parallel connection
300 still active after TC shutdown threshold expired. ((1) Module
300 DFHZSHU).
...
19.19.52 JOB29973 +DFHDU0303I IYNXU Transaction Dump Data set DFHDMPA closed.
19.19.52 JOB29973 +DFHKE1799 IYNXU TERMINATION OF CICS IS COMPLETE.
19.19.52 JOB29973 BPXP018I THREAD 17DD780000000000, IN PROCESS 84083006, ENDED 347
347 WITHOUT BEING UNDUBBED WITH COMPLETION CODE 40222000
347 , AND REASON CODE 00000000.
19.19.52 JOB29973 IEF450I IYNXU CICS730 - ABEND=S222 U0000 REASON=00000000 348
348 TIME=19.19.52
19.19.52 JOB29973 - --TIMINGS (MINS.)-- ----PAGING COUNTS---
19.19.52 JOB29973 -JOBNAME STEPNAME PROCSTEP RC EXCP CPU SRB CLOCK SERV PG PAGE SWAP VIO SWAPS STEPNO
19.19.52 JOB29973 -IYNXU CICS730 *S222 15268 .00 .00 5.61 28100 0 0 0 0 0 1
19.19.52 JOB29973 -IYNXU ENDED. NAME-CICS730 IYNX TOTAL CPU TIME= .00 TOTAL ELAPSED TIME= 5.61
19.19.52 JOB29973 $HASP395 IYNXU ENDED - ABEND=S222
