OY62546: LOOP IN ISTCFCR2 PROCESSING A POWE THAT POINTS TO ITSELF. FIXED IN OY64169.

APAR status

• Closed as returned (APAR cannot be resolved without additional info from IBM or customer.)

Error description

• VTAM goes into a loop and will not respond to commands.
  The loop is in module ISTCFCR2 processing a POWE that points to
  itself at offset 8. ISTCFCR2 is running on the CPMSG PAB.
  

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

• APAR OY62546 is being returned for additional documentation.
  ISTCFCR2 is looping because a POWE on the wait queue is pointing
  to itself. POWEs on the wait queue represent WTORs and
  incomplete MLWTOs.  ISTCFCR2 is looping in LMA (Lost Message
  Array) processing. This code is entered if there is an LMA entry
  built as the result of an abend or a CLOSE ACB for an appl that
  is authorized to do SENDCMDs and RCVCMDs. In this case an abend
  in ISTINCTS caused the LMA entry to be built by ISTAPCES.
  The purpose of the LMA processing is to throw away incomplete
  message groups associated with a process that will be unable to
  complete the group.
  
  It cannot be determined from the documentation the cause of the
  POWE pointing to itself.
  Several probes have been written to detect this condition, to
  cause a full dump to be taken, and to zero the forward pointer
  in the POWE so that the loop will not occur. One probe is in
  module ISTCFCTM after POWEs are added to the wait queue, and
  four probes are in module ISTCFCR2 at the points where the wait
  queue is scanned. It should be noted that there is a possibility
  that the loop could be encountered within internal macro code
  (for example, when the chain is run to remove a POWE from the
  queue) that cannot be detected with a probe.
  
  In addition to the probes, the VIT should be running either
  externally or with a large internal trace table with VIT
  options of SMS, MSG, and PSS.
  

APAR Information

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

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

Fix information

Applicable component levels