CICS task in tight loop not abending AICA after RUNAWAY interval

Question & Answer

Question

Why would a CICS user task fail to abend with an AICA when the task is in a tight loop on an open TCB and runs longer than the runaway task time interval specified by the ICVR system initialization parameter? I am running CICS Transaction Server for z/OS (CICS TS) V4.2 and Xpediter for CICS V9.4.

Answer

Compuware has provided a PTF XDPO099 for Xpediter for CICS 9.4 to resolve this loop in XPCTA exit at abnormal task termination.

Review of a system dump at the time of the loop, shows the task is in a tight loop in Compuware program DBUGCXI. This is a global user exit (GLUE). When CICS gives control to GLUEs it turns off the runaway task mechanism, as seen in the TASENTRY control block (TAS_RUNAWAY_STOPPED is set on).

You can enter IPCS command IP SYSTRACE to display the system trace. For this problem, the system trace shows the following repeated entries on the L8 TCB:

   ---------------------------------------------------------  
  WU-Addr- Ident  CD/D PSW----- Address-  Unique-1 Unique-2 
  009A9588  PC     ...   8      1EFED35D              13706 
  009A9588  PR     ...   4      1EFED35D 149DD558           
  009A9588  PC     ...   8      1EFED35D              13706 
  009A9588  PR     ...   4      1EFED35D 149DD558           
  009A9588  PC     ...   8      1EFED35D              13706 
  009A9588  PR     ...   4      1EFED35D 149DD558           
  009A9588  PC     ...   8      1EFED35D              13706 
  009A9588  PR     ...   4      1EFED35D 149DD558           
  009A9588  PC     ...   8      1EFED35D              13706 
 ----------------------------------------------------------

From IPCS Option 1, you can browse storage and input the "Address" from the trace. In this case, Address 1EFED35D pointed into module DBUGCXI.

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSGMGV","label":"CICS Transaction Server"},"Platform":[{"code":"PF035","label":"z\/OS"}],"Component":"","Version":"","Line of Business":{"code":"LOB35","label":"Mainframe SW"}}]

Product Synonym

CICS/TS CICSTS CICS TS CICS Transaction Server

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Document Information

Modified date:
18 May 2016

UID

dwa1270827

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