PK29657: CICS TS 3.1 TASK IS IN HARD LOOP LOOPING AFTER A PROGRAM CHECK LOOP OCCURS DFHWBXM RELEASE_XM_CLIENT AND DFHWBCL

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You are running CICS Transaction server 3.1 and have a WEB
  transaction that experienced a program check - ABEND0C1.
  The task then goes into a TIGHT loop, preventing any other work
  from getting done in the CICS region. The region has to be
  recycled. Here is some information from the dump:
  The stack
  @STACK   LEN  TYPE ADDRESS  LINK REG OFFS ERROR NAME
  36CF9020 0130 Bot  B5801A00 B5801DAC 03AC       DFHKETA
  36CF9150 0310 Dom  B5819AB8 B5819CC0 0208       DFHDSKE
  36CF9460 0530 Dom  B583F2D0 B58404A0 11D0       DFHXMTA
  36CF9990 0A20 Dom  B6000000 B6000996 0996       DFHWBXM
                Int     +07EC B60001F4 01F4
                                               RELEASE_XM_CLIENT
  Looking at SYSTRACE, focusing on the PSW addresses in the
  DSP entries, they pointed to the following modules:
  x'9A0' into DFHWBXM     x'52A' into DFHKEDCL
  x'214' into DFHKEDRT    x'968' into DFHWBXM
  x'964' into DFHWBXM     x'8CC2'into DFHWBCL
  x'178' into DFHWBCL     x'548' into DFHKEDCL
  x'8CB6'into DFHWBCL     x'17C' into DFHWBCL
  x'18A' into DFHWBCL
  DFHWBXM calls DFHWBCL to do a Close_session.  The first thing
  WBCL does is a validate session token.  This fails, so it
  simply returns to WBXM who is not checking the return code
  and calls WBCL again.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All.                                         *
  ****************************************************************
  * PROBLEM DESCRIPTION: Loop in CICS after program check within *
  *                      alias task.                             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A web request is being processed by CICS, and the CICS alias
  task issues an outbound HTTP request. Before the outbound
  request is closed a program check occurs. During abend
  processing LE issues an abend with the CANCEL option which
  ensures any alias task abend handlers are not invoked. During
  transaction termination, RELEASE_XM_CLIENT is invoked because
  the wb transaction token is non zeros. Webrequest_tidyup is
  called, which clears both parts of the transaction token,
  WRB_ptr and WBO_anchor. Later in a loop to clear the WBO
  sessions we issue close_session for each WBO found but do not
  check the response. Because webrequest_tidyup has cleared the
  WBO_anchor, the close_session fails and so we do not remove the
  session. The next iteration of the loop picks up the same
  session and hence a tight loop in CICS. As we are in transaction
  termination, runaway timer has been disabled so the loop does
  not time out. CICS has to be cancelled.
  

Problem conclusion

• Webrequest_tidyup has been changed to clear only the top half of
  the transaction_token (wrb_ptr) and leave the bottom half
  (wbo_ptr). This enables DFHWBXM to clean up the sessions
  correctly.
  

Temporary fix

•             *********
              * HIPER *
              *********
  FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UK18540

Modules/Macros

•    DESWBA   DESWBAP  DESWBBLI DESWBDM  DESWBRQ
  DESWBSR  DESWBXM  DESWBXN  DFHWBA   DFHWBAP  DFHWBAPF DFHWBBLI
  DFHWBDM  DFHWBRQS DFHWBSR  DFHWBXM  DFHWBXN
  

Fix information

• Fixed component name

  CICSTS 3.1 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK18540

     UP06/10/06 P F610

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.