PM81491: HUNG IN DSNTABA

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• If Lock Timeout happens, DSNTLSUS calls conversion process. When
  this processing is active, Cancel Thread may be issued. That
  will cause another lock request under the same agent structure,
  which opens the door to messing with the RLPFUSER and other
  fields used in SYNC processing which will make DSNTABA make the
  wrong decision.
  It causes thread is hung in DSNTABA,
  Also ABEND378 RC0000001C will occur if second Lock request will
  finish with a timeout because TRWA196 is already zero.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 users.                               *
  ****************************************************************
  * PROBLEM DESCRIPTION: There are 2 known symptoms:             *
  *                                                              *
  *                      1. A thread hung in CSECT DSNTABA.      *
  *                      2. ABEND378 RC0000001C RC1C as a        *
  *                         result of a call from CSECT          *
  *                         DSNTLSUS.                            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A thread involved in an IRLM timeout may require a UTF/EBCDIC
  conversion. Internal routine to preform such conversion may
  issue another IRLM call under the same DB2 agent structure.
  At this point there are 2 possible cases:
  
  1. If the subsequent request times out, it will incorrectly
  free internal agent storage and return.  The original IRLM
  request will attempt to free the same storage and result in
  ABEND378 RC0000001C RC1C.
  
  2. If the original request was cancelled while suspended in
  IRLM, but was already involved in partial timeout processing in
  IRLM before the cancel, the subsequent request will clear
  out an internal pointer upon its completion.  DB2 system agent
  uses this pointer during abort processing to see if SYNC should
  be preformed on the original IRLM request, and will inocrrectly
  issue the IRLM SYNC request. This will result in a hang of this
  system agent in CSECT DSNTABA
  

Problem conclusion

• Change DB2 logic to avoid issuing a lock request during the
  UTF/EBCDIC conversion.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK92333 UK92334

Modules/Macros

•    DSNTLSUS
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK92333

     UP13/03/26 P F303

• R910 PSY UK92334

     UP13/03/26 P F303

Fix is available

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