IT04071: PCOM: PCSCM CRASH RUNNING SNA 3270 SESSIONS

Personal Communications 6.0.12
Personal Communications 6.0.13
Personal Communications 6.0.15

APAR status

• Closed as program error.

Error description

• There are 3-PCs each are started with 3-session as A,B,C (being
  varied OFF/ON every one minute)
  
  PCSCM.EXE crashed during user operation on SNA 3270 session.
  Pcomm is at 6.0.9 level and connectivity is LAN/LLC2.
  Applied fixes from PMR13985,999,760:
  APPN.sys
  PCSWS.exe
  PCSCM.exe
  pcstlnet.dll
  pcsruiss.dll
  pcsruisn.dll
  pcsruinw.dll
  
  operation: At PC1, start 4-session at 17:50 on 2014/05/27
  session does not have any error till 07:00 on 2014/05/28
  then stop all sessions then try to start a session, PCSCM.exe
  is crashed,
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All PCOM 3270 SNA LLC2 users with sessions   *
  *                 running for a long period of time            *
  ****************************************************************
  * PROBLEM DESCRIPTION: IBM Personal Communications 3270 SNA    *
  *                      LLC2 session may crash while closing    *
  *                      the session after a long run.           *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  This problem is a regression of APAR IC80784. Closing the
  session may cause a crash due to access violation.
  
  There are two symptoms observed:
  1. Crash because of an attempt to free a memory block which is
  already freed.
  2. Free memory block chaining pointer becomes null.
  This APAR addresses symptom #1.
  
  A race condition betweeen session initiation/termination (the
  condition of IC80784) and process termination of pcsws.exe
  causes duplicate memory free.
  

Problem conclusion

• PCSTQ.DLL module has been corrected not to free a memory block
  whose memory block header does not indicate allocated status.
  
  Fix scheduled for PCOM 6.0.12 Refresh Pack
  

Temporary fix

Comments

APAR Information

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

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

Modules/Macros

• PCSTQ
  

Fix information

• Fixed component name

  PCOMM V5 COMBO-

• Fixed component ID

  5639I7000

Applicable component levels

• R609 PSY

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