Table of Contents


  1. Preface
  2. Introduction to PowerExchange
  3. DBMOVER Configuration File
  4. Netport Jobs
  5. PowerExchange Message Logs and Destination Overrides
  6. SMF Statistics Logging and Reporting
  7. PowerExchange Security
  8. Secure Sockets Layer Support
  9. PowerExchange Alternative Network Security
  10. PowerExchange Nonrelational SQL
  11. DTLDESCRIBE Metadata
  12. PowerExchange Globalization
  13. Using the PowerExchange ODBC Drivers
  14. PowerExchange Datatypes and Conversion Matrix
  15. Appendix A: DTL__CAPXTIMESTAMP Time Stamps
  16. Appendix B: PowerExchange Glossary

DM_SUBTASK Statement

DM_SUBTASK Statement

The DM_SUBTASK statement controls how the PowerExchange Listener accesses the file that stores data maps.
Use this statement to reduce overhead in an environment where multiple PowerExchange Listeners are running and make frequent open and close requests on the data map file.
  • N
    . PowerExchange opens and closes the DATAMAPS data set in PowerExchange Listener subtasks, as required.
  • R
    . To improve the read performance for data maps, the PowerExchange Listener starts a subtask that opens the DATAMAPS data set in read mode. No change in processing or performance occurs for insertion and deletion of data maps.
    The R option is faster than the N option but slower than the Y option.
  • Y
    . A single PowerExchange subtask owns and opens the DATAMAPS data set. All other subtasks use the data map subtask to access data maps. The DATAMAPS data set remains open until the PowerExchange Listener is shut down.
    Enter Y to decrease resource utilization and improve the performance of the PowerExchange Listener. PowerExchange opens that DATAMAPS data set one time during the life of a PowerExchange Listener address space instead of opening and closing the data set for each request.
    If you enter Y and also define the DATAMAP_SERVER statement, PowerExchange designates the PowerExchange Listener as a data map server.
Default is N.
  • If you specify DM_SUBTASK=Y and also specify 2 for the first parameter of the SECURITY statement, PowerExchange checks this resource profile to determine whether to permit access to the DATAMAPS data set. In this case, you must code the resource profile in your security system and grant access to all users that read or write data maps on z/OS.
    By default, PowerExchange checks the DTL.DATAMAP.DATASET resource profiles in the FACILITY class. The profile name and class might be different if you specify other values on the DM_RESOURCE and RACF_CLASS statements.
  • If you specify DM_SUBTASK=Y and a PowerExchange Listener holds an exclusive lock on the DATAMAPS data set, also enter DATAMAP_SERVER=
    to enable other tasks, such the IMS synchronous ECCR or a netport job, to access the data set. Otherwise, the tasks fail.
    Alternatively, use data maps caching. Informatica recommends this approach to improve performance and to avoid access problems that can occur if the PowerExchange Listener data maps server stops. To implement data maps caching, specify DM_SUBTASK=R and DMXCACHE_MAX_MEMORY_MB=20. With these settings, the PowerExchange Listener opens the data set in read-only mode and allows other tasks to access the data set.


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