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CFSizer Alternate Sizing Techniques

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Alternative methods for calculating required structure sizes based on existing structure sizes

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The following methods can be used to calculate required structure sizes based on existing structure sizes:

  1. If a coupling facility (CF) at the new CFLEVEL is accessible in your configuration and is defined in the CFRM policy, structure rebuilds from lower-level CFs to higher-level CFs resize the structure automatically based on its current structure object counts. The CFRM policy can then be adjusted according to the size of the structure when it is allocated in the higher-level CF.

    Note that rebuild does not resize the structure and instead attempts to allocate it at the size specified in the CFRM policy or by the structure connectors) under the following circumstances:
    • When a CFRM policy change is pending
    • When a connector changes the structure attributes on its IXLCONN REBUILD request.

  2. There is a utility called SIZER that is available for download as a zipped package containing the following files:
    sizer.obj Sizer utility executable (binary, FB 80)
    runsize.jcl JCL to run the utility, as a batch job or as a started task (binary, FB 80)
    linksize.jcl Link-edit JCL (binary, FB 80). Update this JCL to install the utility in an authorized library.
    The Sizer Utility Program.doc Utility documentation (Microsoft Word document)

    This utility, provided as is and not formally supported by IBM, will size currently allocated structures for each of the CFs in your CFRM policy that are online and accessible to the system running the utility.

    SIZER is useful when you are already confident that your existing structures are adequately sized for their current workload and you simply want to know how much they may need to grow to accommodate the same workload at the new CFCC level. To use it for that purpose, you must sequence your CF migration so that you have at least one CF at the current CFCC level and one CF at the new level installed and operational at the same time. With all structures in the current (lower-level) CF(s) and none in the new (higher-level) CF, run the SIZER utility. The result is a list of all allocated structures, each with a table of attributes, object counts, and the structure size needed to support those attributes and counts in each available CF.

    The upgrade scenario would be similar to the following: 

    1. Move all structures out of the first CF to be upgraded.
    2. Upgrade the CF to the desired CFLEVEL.
    3. Run the SIZER utility with all structures allocated in a CF at the original CFLEVEL.
    4. Using the utility output, update the CFRM policy to reflect the sizes required at the higher CFLEVEL and any necessary changes to the structure preference lists.  Rebuild to activate the policy and distribute the affected structures into the upgraded CF.
    5. Upgrade the rest of the CFs and distribute the structures as desired.

    The current version of the utility, dated 10/07/16, is attached to this document.

The FMID visible in the eyecatcher of the utility OBJ is not relevant.  The utility runs on any in-service release of z/OS.

Please send any comments, suggestions, or problems related to the SIZER utility to

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Document Information

Modified date:
12 October 2021