• 1.  Is anyone using IDMS multi-tasking?

    Posted Dec 21, 2016 09:41 AM

    We're looking at activating MT. We're curious how wide spread the use of MT is.

  • 2.  Re: Is anyone using IDMS multi-tasking?

    Posted Dec 21, 2016 04:09 PM
      |   view attached

    I have been using multitasking on our back-end CVs for 10? Years – the increase cpu was negligible, and the improvement in throughput was noticeable.

    When run depth = 3, subtasks = 6m and ziip = y


    At our peak, we were running 500 million tasks / week – a bit less now – but still great



    The only problem we ever head – on front end cvs – we had issues when multitasking tasks were wt8ingi9ng to the internal reader – got cv-ending abends – but there is an optional bit that my correct that now


    Chris Hoelscher

    Technology Architect, Database Infrastructure Services

    Technology Solution Services


    123 East Main Street

    Louisville, KY 40202

    (502) 714-8615, (502) 476-2538

  • 3.  Re: Is anyone using IDMS multi-tasking?

    Posted Dec 23, 2016 09:38 AM

    Mark,  I used MT with good success at my previous employer and have implemented it at two client sites as a consultant.  You might want to start small and increase the count based on observations.

  • 4.  Re: Is anyone using IDMS multi-tasking?

    Posted Dec 21, 2016 07:41 PM



    We run an MT level of 4 on a box with 3 GPs.




    Charles (Chuck) Hardee<>

    Senior Systems Engineer/Database Administration

    EAS Information Technology<mailto:DBA%20Engineering%20-%20DB2_IDMS>


    Thermo Fisher Scientific

    300 Industry Drive | Pittsburgh, PA 15275

    Phone +1 (724) 517-2633 | Mobile +1 (412) 877-2809 | FAX: +1 (412) 490-9230<>  |


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  • 5.  Re: Is anyone using IDMS multi-tasking?

    Posted Dec 23, 2016 11:18 AM

    Hi Mark, before activation of MT, check the effectiveness of MVS cpu allocated by z/OS to your IDMS region. It is useless or even painful to allocate extra TCB's to your IDMS region if z/OS doesn't allocate now enough CPU to your IDMS region. MT uses MPMODE locking which consumes extra CPU.
    After MT activation, watch your TCB's usage with DCMT DIS MPMODE and DCMT DIS SUBTASK EFFECTIVENESS .                                                                                         

  • 6.  Re: Is anyone using IDMS multi-tasking?

    Posted Dec 27, 2016 08:28 AM

    In support of Philippe’s comments…..



    In a really enjoyable past life, to meet “Six Sigma” belt requirements, we did “tuning” projects. This for all of GE’s DBDC environments, CICS,  DB2, IDMS & etc, and their associated products.


    This was a “speed and profitability” analysis. AKA “do it faster and lower CPU”.


    We examined and analyzed every IDMS user setting, including the famed “Bob Dobbs zaps”, with actual production work loads.


    The result for IDMS multitasking and I quote “Recommendation: Turn off multitasking. Unless the region is , It is unlikely that the region requires multiple TCBs to get the requested work done. The IDMS multitasking option can cause the region to consume 20% more CPU to manage the additional TCBs.”


    No region at GE benefited from multitasking.


    When I arrived here multitasking was turned on. I exercised the sigma project here. End result was multitasking was turned off, while implementing other “speed and profitability” recommendations. The average reductions were 37%  CPU and 20% response.


    I sure do miss my former GE “CDAC” peers, Ron Lamb, Dan Hall, Brian Schroeder, Doug Jolley, Jack Koebbe, George Cable, Gerry Irwin and Dave Burton.

  • 7.  Re: Is anyone using IDMS multi-tasking?

    Posted Jan 03, 2017 10:27 AM

    Some IDMS sites would get minor advantages of MT. I am thinking about site using IDMS only as a DataBase server with DB requests coming only from CICS and Batch programs. MPMODE DB will be the most used in this configuration as almost none user code is running inside the CV and MPMODE locking will restrict the usage of only 1 TCB.

    On a site using IDMS/DB/DC with user code running inside the CV, the several MPMODEs will be dispatched into the multiple TCB's assigned to IDMS.

    In every situation, deployment of MT must be monitored on a regular basis.

  • 8.  Re: Is anyone using IDMS multi-tasking?

    Posted Jan 02, 2017 11:32 AM

    Interesting comments Rob.  I wonder if John Siraco would like to add anything.