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Status Not under consideration
Workspace CICS Transaction Server for z/OS
Categories Runtime
Created by Guest
Created on Mar 2, 2012

RELATED IDEAS

CPU usage of DFHEIP increased a lot after hardware upgrade to z196

We measure our CICS systems daily with Strobe. After upgrading our hardware from a z10 to a z196 we observed that the propotion of the CPU usage increased
a lot ( more than three times ). First we thought that this is a Strobe problem, but Compuware knows the problem from other clients. Their statement is, that the values are true and that the reason for the
increase is caused by the SPKA instruction which is used in the CSECTDFHEIP. Here their statement:
CSECT DFHEIP contains SPKA instructions. One is executed to ensure CICS code runs in Key8. It is executed soon after getting control to
service an EXEC CICS command. The other is executed just before control returns to the application. It is to set the PSW key back to what it was in the application.
There is a requirement to CICS developement requesting that they change DFHEIP so that SPKAs are not done when they are not necessary.
That requirement number is MR1006112419 .
------------------------------------------------------------------------

We executed a detailed Strobe report to examine this. From our oberservation we can confirm this. The CPU is used in a code part ( length 64 Byte ), which contains the SPKA instruction.
In the above mentioned PMR there are appendixes where you can the real figures.

Idea priority Urgent
  • Guest
    Reply
    |     Oct 5, 2015

    Due to processing by IBM, this request was reassigned to have the following updated attributes:
    Brand - Servers and Systems Software
    Product family - Transaction Processing
    Product - CICS Transaction Server

    For recording keeping, the previous attributes were:
    Brand - WebSphere
    Product family - Transaction Processing
    Product - CICS Transaction Server

  • Guest
    Reply
    |     Jun 16, 2012

    We have no plans to introduce code into DFHEIP to avoid SPKA instructions. We wish user to run with storage protection active and SPKA is required for this. Hursley analysis of HIS data indicates the customer is receiving the benefits from the z/196 in line with LSPR projections.
    As agreed on the conference call on June 15th 2012, this RFE is being closed.

  • Guest
    Reply
    |     Mar 6, 2012

    Magnus,
    It would help us a lot if you were able to send the full Strobe reports comparing z10 and z196.
    Also could you tell us about when you run with STGPROT=NO and when with STGPROT=YES. With STGPROT=YES there is no possibility to avoid the SPKA instructions in DFHEIP.
    thanks,
    Ian J Mitchell

  • Guest
    Reply
    |     Mar 5, 2012

    Magnus, we need to validate the scope of the problem you've identified before responding. I'm sure you will appreciate the sensitivity associated with performance and we don't want customers without all of the context of your investigations to be worried that there is a general problem with CICS on z196. We are very keen to understand more about the data you've collected so that we do understand the extent of the problem better - making it private is not a sign we wish to sweep anything under the carpet. We are working on similar concerns from other angles, so please rest assured we're taking this seriously.

    Ian J Mitchell, CICS Portfolio Architect

  • Guest
    Reply
    |     Mar 5, 2012

    Please change the visibility to 'Public'.

  • Guest
    Reply
    |     Mar 2, 2012

    Attachment (Description): The code

    P47174_DFHAIP_C...
    P47174_DFHAIP_CODE.txt
     P47174_DFHAIP_CODE.txt
    Open full size
    P47174_DFHAIP_CODE.txt
  • Guest
    Reply
    |     Mar 2, 2012

    Attachment (Description): A sample of a strobe report.

    p47174_Strobe_R...
    p47174_Strobe_Report.txt
     p47174_Strobe_Report.txt
    Open full size
    p47174_Strobe_Report.txt
  • Guest
    Reply
    |     Mar 2, 2012

    Attachment (Description): Explanation in the dataset

    P47174_DFHEIP_P...
    P47174_DFHEIP_PORTION.txt
     P47174_DFHEIP_PORTION.txt
    Open full size
    P47174_DFHEIP_PORTION.txt

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