PK50759: NOTICEABLE INCREASE IN CPU WHEN USING WEB SERVICES IN CICS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Trying to launch an Application using Web Services in CICS
  caused a noticeable increase in CPU usage.  The reason for the
  high CPU was because the output from the customer's webservice
  request consists of a large volume of fields.  The amount of
  generated XML is approximately 380K.  So this partly explains
  the overhead of runing DFHPIII PARSE_ICM.  However, the caller
  of DFHPIII (DFHPITL) passes a default 32K buffer to DFHPIII.
  This is never large enough to hold the output.  DFHPIII
  actually constructs all the XML fragments (in a work buffer)
  and keeps track of the cumulative size of generated XML.
  DFHPIII then returns a BUFFER_OVERFLOW response to DFHPITL
  informing it of the required buffer size. DFHPITL then frees
  off the old 32K buffer and getmains a larger buffer before
  calling DFHPIII a second time.  So each webservice request is
  having to go through DFHPIII 2 times over.  Each webservice
  defined to CICS has a Webservice control block 'pi_wsbcontrol'
  used to hold state information.  So it should be possible to
  record the required XML buffer size for each individual
  webservice (by effectively maintaining a high-watermark value).
  This size can then be used on future invocations of the
  webservice in preference to the default 32K buffer. This
  high-watermark value should (over time) eliminate these
  BUFFER_OVERFLOW conditions and reduce the overhead of DFHPIII
  PARSE_ICM processing.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All CICS users.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Excessive CPU overhead when delivering  *
  *                      webservice responses over 32K.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When the webservice pipeline generates a webservice response
  which exceeds 32K, there are 2 calls to DFHPIII for function
  PARSE_ICM.
  The first call from DFHPITL passes a 32K buffer to hold the
  response. DFHPIII works out the actual size of the SOAP/XML
  response and returns this value to DFHPITL. DFHPITL then
  getmains a larger buffer and calls PARSE_ICM a second time.
  The PARSE_ICM call is quite CPU intensive so duplicate calls
  to this function increase region CPU times.
  
  ADDITIONAL KEYWORDS :- PERFM
  

Problem conclusion

• DFHPITL has been changed to monitor the size of SOAP/XML
  responses for individual webservices. A high watermark response
  size is maintained (subject to a cap of 5-megabytes) and this is
  used as the buffer size for future PARSE_ICM calls for the
  individual webservice.
  

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:

  UK34220 UK34221

Modules/Macros

•    DESPIDC  DESPIDUF DESPITL  DESPIWR  DFHPIDCC
  DFHPIDCD DFHPIDUF DFHPITL  DFHPIWR
  

Fix information

• Fixed component name

  CICSTS V3 Z/OS

• Fixed component ID

  5655M1500

Applicable component levels

• R400 PSY UK34220

     UP08/03/06 P F803

• R500 PSY UK34221

     UP08/03/06 P F803

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.