PM71856: CANCEL THREAD COMMAND MAY NOT COMPLETE FOR TCP/IP CONNECTION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DB2DDF defects 153134 d153134 157665 d157665 pm71856 dpm71856
  -CANCEL THREAD was attempted for a TCP/IP connection. The
  command was not honored. The TCP/IP DROP command had to be
  used to terminate the connection, which allowed the thread to
  terminate.
  
  After applying this change, a RACF PERMIT will be necessary
  for MVS.VARY.TCPIP.DROP for the OPERCMDS class.
    Attribute = CNTLATTR (Control Access)
    Entity    = MVS.VARY.TCPIP.DROP
    Class     = OPERCMDS
  
  ************************************************************
  Additional Symptoms and Keywords:
    Cancel Thread CancelThread
    Hang Hung Wait WT
  
    ABEND47B AB47B S047B 47B 47B-00000000 00000000 RC00000000
    ABEND0C4 AB0C4 S00C4 0C4 0C4-00000011 00000011 RC00000011
      DSNLCSRR DSNLCSRR+0F10 0F10 OFFSET0F10
    DSNV086E MSGDSNV086E 00E50054 RC00E50054
    ABEND04E AB04E S004E 04E 04E-00E50701 00E50701 RC00E50701
      DSNVEUS2 DSNVEUS2+0A2A 0A2A OFFSET0A2A
    During STOP DB2 MODE FORCE (after STOP DDF MODE FORCE ).
    Threads were allowed to incorrectly survive through a
    STOP DDF MODE FORCE and became problematic when encountered
    during subsequent STOP DB2 MODE FORCE processing.
  
    ABEND0C4 AB0C4 S00C4 0C4 0C4-00000004 00000004 RC00000004
      DSNLIRCA DSNLIRCA+05A2 05A1 OFFSET05A2
    OVERLAY OVERLAID OVLY
    After DDF is restarted following a STOP DDF MODE FORCE.
    Threads were allowed to incorrectly survive through a
    STOP DDF MODE FORCE and became problematic once DDF was
    restarted.
    MSGICH408I ICH408I MVS.VARY.TCPIP.DROP OPERCMDS
      After applying this change, users may observe an ICH408I
      message regarding "MVS.VARY.TCPIP.DROP CL(OPERCMDS)"
      authority. This occurs because the change utilizes a TCP/IP
      Drop API (NWMServices64 NWMDropConnType). A PERMIT will be
      necessary for MVS.VARY.TCPIP.DROP for the OPERCMDS class.
        Attribute = CNTLATTR (Control Access)
        Entity    = MVS.VARY.TCPIP.DROP
        Class     = OPERCMDS
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Distributed Data Facility (DDF) users.   *
  ****************************************************************
  * PROBLEM DESCRIPTION: DB2 z/OS threads may not terminate      *
  *                      after being cancelled if the thread     *
  *                      is waiting for a reply from a remote    *
  *                      downstream location (via a TCP/IP       *
  *                      connection).                            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  APAR PM54383 introduced support to allow thread cancel events
  to be honored when the thread is cancelled while waiting for a
  TCP/IP reply from a remote downstream location. This function
  utilizes a TCP/IP Drop API, implemented via APAR PM48851, which
  requires DB2 to determine the TCP/IP connection number
  associated with the downstream connection.
  In environments where DB2 may be associated with multiple IP
  addresses, such as DB2 data sharing environments where DVIPAs
  are defined, DB2 may not be able to determine the TCP/IP
  connection number because TCP/IP may associate the connection
  to a local IP address that DB2 is unaware of (and which is not
  reflected in DB2 Display DDF command report). The absence of
  the TCP/IP connection number knowledge prevents DB2 from being
  able to successfully Drop the connection during cancel events
  and hence the cancel event will not be fully honored.
  To allow the thread termination to complete, intervention will
  be required to terminate the TCP/IP connection to the remote
  downstream location. This intervention procedure is currently
  documented in the "Usage notes" section of the DB2 for z/OS
  "CANCEL THREAD" command in the DB2 for z/OS Command Reference
  manual.
  
  Additional Keywords:
  IDAAV2R1/K IDAAV3R1/K
  

Problem conclusion

• DB2 has been changed to obtain the correct local IP address
  associated with the downstream connection. This allows the
  associated connection number to also be obtained and hence
  allows cancel events to be fully honored.
  After applying this change, a RACF PERMIT will be necessary
  for MVS.VARY.TCPIP.DROP for the OPERCMDS class.
  

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:

  UK82421 UK82422

Modules/Macros

• DSNLIAAC DSNLIRQP
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK82421

     UP12/10/24 P F210

• R910 PSY UK82422

     UP12/10/24 P F210

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.