PK99316: REDUCE EXPOSURE TO MESSAGE DFHIS1022

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You receive message DFHIS1022 Protocol error (code X'061D')
  occurred on RECEIVE IPIC session in IPCONN ipconn.
  The connection error is due to no ISSBs being available to
  process incoming requests from CTG.  The dumps indicate that
  CICS and CTG are out of step with their respective views of
  session availability.
  As soon as a mirror task sends its last response, CTG will
  assume that a session becomes available.  The mirror task on
  CICS will try to free its receive session after sending this
  last response.  However, the logic of freeing the session
  includes a call to user domain for function DELETE_USER.
  This requires the USADLOCK.  If another task holds this lock
  and is stuck because of a bottleneck in the external security
  manager (ESM), then the freeing of the IPIC session ( ISSB)
  will get delayed.  CTG believes that all these sessions are
  available so keeps sending new requests up to CICS.
  Eventually all the available sessions become allocated and the
  next CTG request for a given IPCONN will result in a
  DFHIS1023 message and an error response back to CTG.  CICS uses
  the only system ISSB for the affected IPCONN to deliver this
  error response.
  If yet another request arrives while the system ISSB is
  in use then this gives rise to the DFHIS1022 and CICS
  will try to PURGE all mirror tasks associated with the affected
  IPCONN. If this happens CTG is forced to establish a new
  connection and create a new IPCONN.
  DFHISAL can be changed to defer the DELETE_USER call until after
  the ISSB is released to the free pool. This will ensure that any
  bottleneck in the ESM will not lead to a DFHIS1022 error.
  Additional Symptom(s) Search Keyword(s):
  MSGDFHIS1022 MSGDFHIS1023
  KIXREVSLY
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: DFHIS1023 and DFHIS1022 can occur when  *
  *                      there is a bottleneck in the external   *
  *                      security manager.                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A condition developed where the limit of available sessions for
  a CICS Transaction Gateway IPCONN was reached. At this point
  CTG stops sending further requests into CICS.
  Some mirror tasks owning these sessions now send their final
  responses to CTG and enter transaction termination. They call
  DFHISAL for function FREE_RECEIVE to release their sessions.
  DFHISAL calls DFHUSAD function DELETE_USER just before placing
  the session on the free chain.
  The DELETE_USER calls got held up due to a bottleneck in the
  external security manager. In this window CTG started sending
  new requests into CICS as sessions were now deemed to be
  available from its perspective.
  CICS is unable to allocate sessions for these new requests.
  This initially causes a DFHIS1023 conversation error with reason
  code 061D but can lead to a DFHIS1022 connection error
  with reason code 061D which causes the IPCONN to be released.
  

Problem conclusion

• DFHISAL FREE_RECEIVE processing has been changed so that the
  DFHUSAD DELETE_USER call is deferred until after the ISSB
  ( IPCONN session ) has been placed on the free chain.
  

Temporary fix

• 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:

  PM02642 UK53362

Modules/Macros

•    DESISAL  DFHISAL
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R500 PSY UK53362

     UP10/01/08 P F001

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.