PM04061: CICS WEB SERVICES PERFORMANCE. TCP/IP NAGLE ALGORITHM RESULTS IN UNNECESSARY DELAYS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• You are using CICS Web Services, without SSL or IPIC
  involvement. You notice delays for small packets being sent out
  by TCP/IP.
  TCPIP's use of the Nagle algorithm is adding unnecessary delays
  and causing performance issues in CICS.  There is no way for you
  to specify 'TCP_NODELAY' to override the default behavior.
  .
  Additional Symptom(s) Search Keyword(s):
  socket wait delay Nagel RFC 896 getsockopt setsockopt NODELAY
  ACK NODELAYACKS
  .
  KIXREVNDB
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance degradation may occur when  *
  *                      sockets domain sends messages using     *
  *                      TCPIP.                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  By default, TCPIP uses the Nagle algorithm for all data sent
  over a socket. This can lead to delays in the delivery of
  network messages.
  
  CICS already disabled the Nagle algorithm when sending response
  data using the IPIC protocol and when using the secure sockets
  layer. The reported problem showed the delays can have a
  noticeable impact for other TCPIP environments.
  

Problem conclusion

• DFHSOLS and DFHSOS10 are changed to set the TCPIP
  TCP_NODELAY option and disable the Nagle algorithm for all
  CICS sockets domain sockets.
  

Temporary fix

• FIX AVAILABLE BY PTF ONLY
  

Comments

APAR Information

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

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

  PM06264 UK55008

Modules/Macros

•    DESSOLS  DESSOSO  DFHSOLS  DFHSOSOC DFHSOS00
  DFHSOS01 DFHSOS02 DFHSOS03 DFHSOS04 DFHSOS05 DFHSOS06 DFHSOS07
  DFHSOS08 DFHSOS09 DFHSOS10 DFHSOS11 DFHSOS12 DFHSOS13 DFHSOS14
  DFHSOS15 DFHSOS16 DFHSOS17 DFHSOS18 DFHSOS19 DFHSOS20 DFHSOS21
  DFHSOS22 DFHSOS23
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R500 PSY UK55008

     UP10/03/12 P F003

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.