PK96953: DELETE_USER COUNT NOT DECREMENT USING EXEC CICS START TWICE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The problem occurs when one transaction starts another
  transaction with EXEC CICS START. The START command (DFHICP)
  calls user domain for ADD_USER_WITHOUT_PASSWORD. This
  increments the use count for the NON-TERMINAL USERID and
  returns a user security token. The token is used to obtain the
  operator priority which is passed on the ATTACH call for the
  new TRANSACTION. ICEUSSET is set in the ICE to ensure that a
  corresponding DELETE_USER call is made after the ATTACH has been
  issued.
  
  After the ATTACH completes, the DELETE_USER call is made.
  However, this call gets stuck because the USADLOCK is busy.
  While the attaching task is suspended, the attached task starts
  running.  The new task performs transaction initialization and
  issues its own call to user domain for
  ADD_USER_WTHOUT_PASSWORD. This also increments the use count
  for the same NON-TERMINAL USERID.
  This completes and the started task also sets ICEUSSET to ensure
  that it performs a DELETE_USER call during transaction
  termination. The attached task eventually suspends and the
  attacher gets going. It completes the DELETE_USER call. DFHICP
  now resets ICEUSSET as the DELETE_USER call has completed.
  
  However, this means that when the attached task reaches task
  termination it finds that flag ICEUSSET in the ICE is OFF. So
  the attached task bypasses its DELETE_USER call.  So the use
  count for the USERID gets incremented twice (by the attacher
  and the attached task) but only decremented once (by the
  attacher).
  

Local fix

• No Local fix
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: The parameter USRDELAY stops working    *
  *                      because USERIDs that are inactive are   *
  *                      marked as in-use due to their           *
  *                      usud_add_use_count being non-zero.      *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  One transaction starts another transaction with EXEC CICS
  START. DFHICP calls user domain for
  ADD_USER_WITHOUT_PASSWORD. This increments the use count for
  the NON-TERMINAL USERID and returns a user security token.
  ICEUSSET is set in the ICE to ensure that a corresponding
  DELETE_USER call is made after the ATTACH has been issued.
  
  After the ATTACH completes, the DELETE_USER call is made.
  However, this call gets stuck because the USADLOCK is busy.
  While the attaching task is suspended, the attached task
  starts running. The new task performs transaction
  initialization and issues its own call to user domain for
  ADD_USER_WTHOUT_PASSWORD. This also increments the use count
  for the same NON-TERMINAL USERID. This completes and the
  started task also sets ICEUSSET (in the same ICE) to ensure
  that it performs a DELETE_USER call during transaction
  termination. The attached task eventually suspends and the
  attacher gets going. DFHICP now resets ICEUSSET as the
  DELETE_USER call has completed. It finds that ICEUSSET is
  off so it does not issue a DELETE_USER call.
  

Problem conclusion

• DFHICP has been amended to reset ICEUSSET flag before the
  DELETE_USER call rather than just after it.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

  PK93366

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

  UK51109

Modules/Macros

• DFHICP
  

Fix information

• Fixed component name

  CICS TS Z/OS V4

• Fixed component ID

  5655S9700

Applicable component levels

• R600 PSY UK51109

     UP09/10/28 P F910

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.