OA28707: XD BUFFERS (XDBUF) LOST WHEN THE OTHER SIDE OF MPC GOES INACTIVE THEN ACTIVE. MPCDYN=YES IS DEFINED.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• XD buffers (XDBUF) lost when the other side of MPC goes inactive
  then active.  MPCDYN=YES is defined. Four (4) buffers are lost
  for each occurrence.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All using Subarea MPC connections with       *
  *                 MPCDYN=YES specified.                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: Subarea MPC connections which           *
  *                      specifiy MPCDYN=YES lose XD buffers     *
  *                      during INOP recovery.                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Sample Configuration:
  
  Two WRITE/READ pair subarea MPC configuration:
  
         |-W1=======R1-|
         |-W2=======R2-|
  VTAM A |             | VTAM B
         |-R1=======W1-|
         |-R2=======W2-|
  
  The problem is summarized as follows:
  1) A 2 READ/2 WRITE subarea MPC connection is activated beteen
     two subarea nodes. MPCDYN=YES is specified on each MPC
     definition.
  2) In this example, Host A issues a V NET,INACT to inactivate
     the MPC line.
  3) VTAM B INOPs the MPC group as both READ devices receive
     unit checks (UC) as a result of the operator command on VTAM
     A.
  4) During recovery of the MPC connection on VTAM B, the
     MPNCB control block is reused during the recovery of the
     INOP 01.
  5) As a result, when the connection is reactivated from VTAM A,
     XID buffers are still chained off the MPNCB from the prior
     connection.  When XID0s and XID7s are exchanged for the
     new activation, the pointers to the old  XID (XD buffer pool)
     are lost.  Specifically, four XD buffers are lost each time
     the connection recovers from an INOP condition.
  
     NOTE: Buffers are not lost on the side which issued the
           V NET,INACT.
  

Problem conclusion

• ISTTSC8X - Segment CLEANUP has been modified to free the
             following XD buffers:
             MPN_OUT_XID0_SAVE
             MPN_IN_XID0_SAVE
             MPN_OUT_XID7_SAVE
             MPN_IN_XID7_SAVE
  
  ISTTSC8E - Included for maintenance purposes.
  

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:

  OA28778 OA28884 UA47196 UA47197 UA47198

Modules/Macros

• ISTTSC8E ISTTSC8X
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R1A0 PSY UA47196

     UP09/06/10 P F906

• R180 PSY UA47197

     UP09/06/10 P F906

• R190 PSY UA47198

     UP09/06/10 P F906

Fix is available

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