PH27736: CORRECT IFAUSAGE FOR MQ JAVA TRANSACTIONS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When a CICS task first uses MQ from Java code an IFAUSAGE
  REGISTER call is made on the T8 TCB.  At the end of the task an
  IFAUSAGE DEREGISTER call is made.  However, this will be made on
  QR or an L8 and will never be made on the original T8 TCB.
  
  The IFAUSAGE DEREGISTER call returns an error, due to being
  issued on the wrong TCB, and leaves the original IFAUSAGE
  registration block associated with the T8 TCB.
  
  Over time these blocks can mount up leading to a performance
  issue when future IFAUSAGE calls are made on that T8 TCB.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Build up of IFAUSAGE registration       *
  *                      blocks due to IFAUSAGE DEREGISTER calls *
  *                      being issued on a different TCB to the  *
  *                      one that issued the REGISTER call.      *
  ****************************************************************
  A switch environment call allows a TRUE to dissociate any state
  from an open TCB when it switches between application
  environments, such as a Java environment, an xplink C
  environment or a regular non xplink, non Java environment such
  as traditional Cobol, PLI, or assembler.
  
  When the CICS-MQ Attach was enhanced to run on any key 8 TCB, it
  was thought that expressing interest in switch environment calls
  was not required because there is no state associated with the
  TCB that needed to be dereferenced. This was incorrect as use of
  IFAUSAGE creates such an affinity.
  
  When a CICS transaction first uses MQ from Java code an IFAUSAGE
  REGISTER call is made on the T8 TCB.  At the end of the task an
  IFAUSAGE DEREGISTER call is made.  However, this will be made on
  the QR or an L8 TCB and will never be made on the original T8
  TCB. The IFAUSAGE DEREGISTER call returns an error, due to being
  issued on the wrong TCB, and leaves the original IFAUSAGE
  registration block associated with the T8 TCB.
  
  
  Over time these blocks can mount up leading to a performance
  issue when future IFAUSAGE calls are made on that T8 TCB.
  

Problem conclusion

• DFHMQTRU will now express interest in switch application
  environment events. When called for switch application
  environment it issues a new SPISWITCH call to MQ. This
  in turn issues the IFAUSAGE calls.
  
  This APAR requires the changes from MQ APAR PH23416 to be
  effective.
  
  MQ APAR PH23416 provides support for the SPISWITCH call. If this
  APAR is not applied the new function will be called but it
  will have no effect. With the MQ APAR applied, IFAUSAGE is
  called when MQ is called for SPISWITCH. This ensures that
  IFAUSAGE-related control blocks are not retained indefinitely
  for the T8 TCB.
  

Temporary fix

Comments

• ×**** PE21/06/03 FIX IN ERROR. SEE APAR PH37824  FOR DESCRIPTION
  

APAR Information

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

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

  UI71284 UI71285 UI71286

Modules/Macros

• DFHEIQMQ DFHMQAEX DFHMQATB DFHMQBAS DFHMQBR9 DFHMQCOD DFHMQCON
  DFHMQCTL DFHMQDIS DFHMQDSC DFHMQDSL DFHMQIG  DFHMQIN1 DFHMQMNS
  DFHMQMON DFHMQPOP DFHMQPRM DFHMQPUL DFHMQQCN DFHMQRET DFHMQRP
  DFHMQRS  DFHMQSSQ DFHMQSTB DFHMQTM  DFHMQTRC DFHMQTRD DFHMQTRI
  DFHMQTRQ DFHMQTRU DFHMQTSK DFHMQXCR DFHMQXTB
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R100 PSY UI71286

     UP20/08/28 P F008

• R200 PSY UI71285

     UP20/08/28 P F008

• R300 PSY UI71284

     UP20/09/09 P F009

Fix is available

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