PH31408: RECURSIVE ATCV ABEND IN CLMT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• In a CPU constraint environment, a CMAS may fail to response to
  the other CMAS, which leads to the termination of the CMAS-CMAS
  connection. Later, the CMAS with lower SYSID, also known as the
  first speaker, will initiate a new connection request to the
  other CMAS (the quiet side). However, due to CPU starvation,
  the previous connection has not yet been able to terminate. The
  CMAS couldn't handle the new request, and CLMT goes into an
  error path. Code added in V5.5 then attempts to reference a
  CLCB control block using a pointer which has not been
  instantiated, which leads to the ATCV abend eventually.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICSPlex SM V5R5M0 and V5R6M0 users.     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Module EYU0CLMT or EYU0CLCT reports an  *
  *                      S0C4 abend while attempting to          *
  *                      establish a new CMAS to CMAS            *
  *                      connection.                             *
  ****************************************************************
  * RECOMMENDATION: After applying the PTF which resolves        *
  *                 APAR PH31408 all CMAS regions must be        *
  *                 restarted. The restarts do not need to       *
  *                 occur at the same time and can occur in      *
  *                 any order.                                   *
  ****************************************************************
  CMAS to CMAS links require a pair of tasks (a send task and a
  receive task) to execute in each region. When two CMAS regions
  establish a new connection, the initial contact transient (ICT)
  module runs to establish a receive task. If the link cannot be
  established (for example a prior link between this pair of
  regions has not yet completely terminated) then the ICT
  attempts to reply to the partner CMAS with an error code.
  
  While handling this error an attempt is made to access the
  link control block (CLCB) but one was never allocated.
  The attempt to access storage linked from the CLCB results
  in an 0C4 abend.
  
  The ICT executes module EYU0CLMT under transaction LNMI for
  connections using the MRO protocol, or EYU0CLCT under
  transaction LNCI for LU62 connections.
  
  Additional Keywords: abend0C4 abendS0C4 abendATCV ConExist
  

Problem conclusion

• EYU0CLMT and EYU0CLCT have been updated to ensure that a CLCB
  is only referenced in the case where one has been acquired.
  

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:

  UI74944 UI74945

Modules/Macros

• EYU0CLCS EYU0CLCT EYU0CLCU EYU0CLMS EYU0CLMT EYU0CLMU EYU0CPAC
  

Fix information

• Fixed component name

  CICS TS Z/OS V5

• Fixed component ID

  5655Y0400

Applicable component levels

• R20M PSY UI74945

     UP21/04/17 P F104

• R30M PSY UI74944

     UP21/04/17 P F104

Fix is available

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