RESOURCE USAGE - IBM Mainframe

The system recourses are such objects as record, disk space, storage space, CPU time, terminal buffer, file control buffer, etc., which are ready to be used by the system control programs and application programs for performing their functions. How the resources are used determines the performance of not only the transaction but also the entire CICS system. Since in on-line environment, many tasks run concurrently, the efficient use of resources is very critical and crucial to the efficiency of the transactions and the CICS system as a whole.

  • The following are some general steps that can be taken to make sure that the effective use of the system resources is taking place:
  • Identify the resources that a program requires and try to use it as little as possible. Conversation is the best strategy for dealing with the issue of resource usage.
  • Use the pseudo-conversational mode, since resources can be made free while the program is waiting for the user's response.
  • Minimize the size of the working storage section, as each task gets a copy of the working storage.
  • Ensure that a program releases a resource that it is holding as quickly as possible.
  • Try to prevent transaction deadlocks.
  • Modularize programs based on functionality, so that some modules can be shared by more than one program. Instead of using CSA, CWA, TWA, TCTUA use EIB information, TSQ with main option, or use the COMMAREA option in the RETURN, XCTL and LINK commands:
  • Instead of using GETMA1N command define the space in the working storage section.
  • Instead of using BDAM, ISAM and QSAM, take advantage of VSAM, the IBM's most reliable primary data access method.
  • Take advantage of VSAM alternate index function.
  • Replace BDAM with VSAM/RRDS, ISAM with VSAM/KSDS and QSAM with VSAM/ESDS.
  • Instead of using the multi-map panel approach use the simple multi-page message (with single map panel) approach.
  • Instead of using the extrapartition TDQ use VSAM/ESDS.
  • Instead of using the intrapartition TDQ use TSQ with MAIN option.
  • Avoid multiple browse operations if possible.

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