Virtual and real storage: performance and tuning

Learn about virtual and real storage use in a z/OS® system and in CICS® regions, and start to monitor performance and tune your use of storage.

Procedure

  1. Understand how virtual and real storage is arranged and managed in a z/OS address space.
    For information about address spaces in z/OS, read the following z/OS documentation:
  2. Understand how virtual storage is arranged and managed when a z/OS address space is used by a CICS region.
    For information about how CICS uses a z/OS address space, see CICS virtual storage.
  3. Monitor and measure the use of virtual storage across your z/OS system using z/OS performance and monitoring tools, such as the z/OS Resource Measurement Facility (RMF).
    For an overview of RMF, see Resource measurement facility (RMF).
    For further information, see the z/OS Resource Measurement Facility (RMF) User's Guide.
  4. Monitor and measure the use of virtual storage and the size of the dynamic storage areas (DSAs) in each of your CICS regions, using the following facilities:
    • The CICS storage manager statistics
    • The reports produced by the sample statistics program DFH0STAT
    • CICS formatted dumps for the loader domain and storage domain
  5. Tune the use of storage across your z/OS system.
    If you are using RMF, for explanations of the RMF reports relating to CICS and to storage, and strategies for tuning, see the z/OS Resource Measurement Facility (RMF) Performance Management Guide and z/OS Resource Measurement Facility (RMF) Report Analysis.
  6. Tune the use of storage in each of your CICS regions, using the methods and suggestions in this section of the information.
    Concentrate on the areas of storage that seem to be the most different from your expectations.