PI06564: EZBITDSA ABEND 4C5 74FF2500 ABEND0C4 EZBUDBYP SP241 TCP ECSA DUCB DUSA SHORTAGE PORT 12001 UCB LOCK

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Outbound traffic backed up on port 12001 waiting on the UCB
  lock.  The lock contention is causing DUCB expansion and
  suspended SRBs that quickly exhaust ECSA.  The current
  design that requires serializing EE outbound requests on a
  given port is unable to sustain high volume traffic.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of the IBM Communications Server for z/OS Version  *
  * 2 Release 1 IP:                                              *
  * Enterprise Extender (EE)                                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Enterprise Extender (EE) outbound traffic causes lock        *
  * content, resulting  in ECSA SP241 storage growth.  Storage   *
  * exhaustion leads to abend 4C5 74FF2500 and abend 0C4.        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply PTF                                                    *
  ****************************************************************
  Enterprise Extender (EE) has a large number pipes and/or ANR
  routed traffic sending high volumes of data outbound.  The EE
  data path for a given network priority will serialize on a
  single UDP port.  The lock contention on the UCB lock for that
  port results in numerous suspended SRBs.  Each suspended SRB has
  an ECSA backed 12K DUCB associated with it.  The delays
  resulting from the lock contention can trigger retransmissions
  that exacerbate the lock contention and ECSA usage.  When ECSA
  becomes exhausted further DUCB expansion will fail with an abend
  4C5 74FF2500 and the outbound data represented in the abending
  request will be dropped.  Additional symptoms include an abend
  0C4 when VTAM is unable to allocate the storage area used to
  pass data to TCP/IP, resulting in EZBUDBYP using an invalid
  storage address.
  
  Consider applying VTAM APAR OA43910 to reduce the number of SRBs
  scheduled to EZBUDBYP to process EE traffic.  There is no
  dependency on the fix for OA43910 when applying this fix.
  

Problem conclusion

• EZBUDBYP has been enhanced to detect UCB lock contention every
  15 outbound requests.  When lock contention is detected the UCB
  lock is released and reobtained to allow the waiting SRBs to
  process.
  

Temporary fix

Comments

APAR Information

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

  PI06478

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

  UI16586

Modules/Macros

• EZBDGDUA EZBDGDUC EZB2LKTB EZBUDBYP
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R210 PSY UI16586

     UP14/04/08 P F404

Fix is available

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