PK65070: CICS TS 3.2 DEADLOCK (CICS HANGS) AFTER TWO USER TASKS WANT SMLOCK AND XMLOCK

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• CICS TS 3.2 deadlock ( CICS hangs) after two user tasks both
  want SMLOCK and XMLOCK at the same time,  other tasks then
  queue in LMLM  for these locks.
  
  Trace of one task shows :
  J9006 DS 0002 DSAT  ENTRY ATTACH                2240A300,0,FD,SY
  J9006 KE 0301 KEIN  ENTRY ADD_DYNAMIC_TASK
  J9006 SM 0301 SMGF  ENTRY GETMAIN               22351458 , 00000
  J9006 LM 0003 LMLM  ENTRY LOCK                21C2C0B0,EXCLUSIVE
  J9006 DS 0004 DSSR  ENTRY SUSPEND        012D0001,,LOCK (SMLOCK)
  
  Trace ot the other task shows:
  QR    DS 0010 DSBR  ENTRY INQUIRE_TASK          198806CF
  QR    DS 0011 DSBR  EXIT  INQUIRE_TASK/OK       QR_TCB
  QR    SM 0D01 SMMF  ENTRY FREEMAIN
  EIQSKTSF,26B49A78
  QR    SM 0D02 SMMF  EXIT  FREEMAIN/OK           USER storage at
  2
  QR    SM 0C01 SMMG  ENTRY GETMAIN
  EIQSKTSG,C8,YES,F
  QR    SM 0C02 SMMG  EXIT  GETMAIN/OK            26B49468
  QR    SM 0E01 SMMC2 ENTRY INQUIRE_TASK_STORAGE
  0092341C,26B49468
  QR    XM 1001 XMIQ  ENTRY INQUIRE_TRANSACTION   0092341C
  QR    LM 0003 LMLM  ENTRY LOCK
  21C2C290,EXCLUSIVE
  QR    DS 0004 DSSR  ENTRY SUSPEND               007D0005,,LOCK
  (XMLOCK)
  
  Both tasks seem to have a valid claim for both SMLOCK and XMLOCK
  but presumably, for task 92341, DFHSMMC2 should release the
  SMLOCK in step "inquire_task_storage" before the
  INQUIRE_TRANSACTION call to to DFHXMIQ which is where the
  XMLOCK is requested.
  

Local fix

• No Local Fix
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: Deadlock between two tasks due to       *
  *                      conflicting XMLOCK and SMLOCK requests. *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  There is a deadlock between a transaction that owns the SMLOCK
  and is waiting for the XMLOCK to be freed, and another that owns
  XMLOCK and is waiting for SMLOCK:
  (1) CICS has attached the CJGC transaction to perform Java
  garbage collection work. The XMAT attach logic requires the
  XMLOCK while it does its work.
  (2) Another task is issuing an EXEC CICS INQUIRE STORAGE call.
  DFHSMMC2 is called to perform INQUIRE_TASK_STORAGE. This holds
  the SMLOCK within DFHSMMC2.
  (3) The attach of CJGC requires storage, so it waits for
  SMLOCK.
  (4) The code in DFHSMMC2 needs to call XM to return
  transactional information, so requires the XMLOCK.
  Keywords: SM XM smmc2 jvm gc
  

Problem conclusion

• DFHSMMC2 has been changed to release and reacquire the SMLOCK
  around the calls to transaction manager for this particular
  operation.
  

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:

  UK38082 PK77869

Modules/Macros

•    DESSMMC2 DFHSMMC2
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R500 PSY UK38082

     UP08/07/17 P F807

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.