PH66879: CICS ATTEMPTS TO OPEN A TCPIPSERVICE ALREADY IN THE OPEN STATUS ON RECEIPT OF ENF 80 SIGNAL

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• CICS v6.2 introduced new functionality to process an ENF 80 and
  automatically reopen TCPIPServices in the event of a TCPIP
  outage. However, in a multi-stack TCPIP environment, or due to a
  timing window with CICS and TCPIP starting at the same time,
  CICS may process the ENF 80 and attempt to open TCPIPServices
  which have already been opened. This causes the affected
  TCPIPServices to be marked closed while retaining an LTE/socket.
  
  The new functionality provides a value to determine whether the
  TCPIPService should be open or not. When testing in a
  multi-stack TCPIP environment, it was found that this value in
  the TCPIPService can be unintentionally reset to closed by an
  INQUIRE_TCPIPSERVICE call. This would mean that a TCPIPService
  which was closed as the result of an outage would not be
  automatically reopened when the ENF 80 is received.
  
  Attempts to manually open the TCPIPService may fail with a
  DFHSO0109 message due to the retained LTE/socket marking the
  port as in use.
  
  For the main issue, some messages like this might be observed
  (with further manual attempts to open the TCPIPService getting a
  similar DFHSO0109 message):
  
  DFHSO0107 01/07/2025 08:37:52 CICSJOB TCPIPSERVICE TEST has
  been opened on port 12345 at IP address 192.XXX.X.X.
  
  DFHSO0109 01/07/2025 08:38:56 CICSJOB The TCPIPSERVICE TEST
  could not be opened because the port 12345 is already in use on
  the IP address 192.XXX.X.X
  
  KIXREVACC
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: CICS attempts to open TCPIPSERVICE      *
  *                      resources in a multi-stack TCPIP        *
  *                      environment which are already open on   *
  *                      receipt of an ENF 80 signal.            *
  ****************************************************************
  A TCPIP stack is taken down and any TCPIPSERVICE resources which
  solely use this stack will subsequently be closed as expected.
  
  When CICS receives an ENF 80 signal to indicate the TCPIP stack
  has restarted, an attempt is made to re-open all TCPIPSERVICE
  resources. This leads to the following problems:
  
  TCPIPSERVICE resources that make use of a different TCPIP stack
  which remained open will have an attempt made to be opened
  again. This causes the following error which results in the
  TCPIPSERVICE closing:
  
  DFHSO0109 01/07/2025 08:38:56 CICSJOB The TCPIPSERVICE TEST
  could not be opened because the port 12345 is already in use on
  the IP address 192.XXX.X.X
  
  TCPIPSERVICE resources that only use the TCPIP stack which was
  taken down will be closed as expected. Performing an INQUIRE on
  these closed TCPIPSERVICE resources whilst the stack is down
  will then lead to the TCPIPSERVICE not being reopened on receipt
  of an ENF 80 signal.
  

Problem conclusion

• CICS has been updated to ensure only closed TCPIPSERVICEs are
  reopened on receipt of an ENF 80 signal.
  
  CICS has also been updated to ensure that performing an INQUIRE
  on TCPIPSERVICE resources whilst the TCPIP stack is down does
  not prevent them from being reopened on ENF 80 signal receipt.
  

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:

  UO07175 UO07176

Modules/Macros

• DFHSOAD  DFHSOCK  DFHSODM  DFHSODUF DFHSOES  DFHSOIS  DFHSOLS
  DFHSOST  DFHSOTB
  

Fix information

• Fixed component name

  CICS TS Z/OS V6

• Fixed component ID

  5655YA100

Applicable component levels

• R500 PSY UO07176

     UP26/03/19 P F603  

• R600 PSY UO07175

     UP26/03/19 P F603  

Fix is available

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