Transaction routing

Review this checklist of the rules and restrictions that apply to transaction routing.

  • A transaction routing path between a terminal and a transaction must not turn back on itself. For example, if system A specifies that a transaction is on system B, system B specifies that it is on system C, and system C specifies that it is on system A, the attempt to use the transaction from system A is abended when system C tries to route back to system A.

    This restriction also applies if the routing transaction, CRTE, is used to establish all or part of a path that turns back on itself.

  • Transaction routing that uses the following “terminals” is not supported:
    • LUTYPE6.1 sessions.
    • IPIC sessions.
    • MRO sessions.
    • IBM® 7770 and 2260 terminals.
    • Pipeline logical units with pooling.
    • MVS™ system consoles. Messages entered through a console can be directed to any CICS® system using the MODIFY command.
  • The transaction CEOT is not supported by the transaction routing facility.
  • The execution diagnostic facility (EDF) can be used in single-terminal mode to test a remote transaction.

    EDF running in two-terminal mode is supported only when both of the terminals and the user transaction are on the same system; that is, when no transaction routing is involved.

    Sending EDF information over an IPIC connection is supported between CICS TS 5.1 or later regions.

  • The user area of the terminal control table terminal entry (TCTTE) is updated at task-attach and task-detach times. Therefore, a user exit program running on the terminal-owning region and examining the user area while the terminal is running a remote transaction does not necessarily see the same values as a user exit running at the same time in the application-owning region. Note also that the user areas must be defined as having the same length in both systems.
  • All programs, tables, and maps that are used by a transaction must be on the system that owns the transaction. The programs, tables, and maps can be duplicated in as many systems as necessary.
  • When routing transactions to or from APPC devices, CICS does not support CPI Communications conversations with sync level characteristics of CM_SYNC_POINT.
  • Terminal control table user areas (TCTUAs) are not shipped when the principal facility is an APPC parallel session.
  • For a transaction started by a terminal-related EXEC CICS START command to be eligible for enhanced routing, all of the following conditions must be met:
    • The START command is a member of the subset of eligible START commands; that is, it meets all the following conditions:
      • The START command specifies the TERMID option, which names the principal facility of the task that issues the command; that is, the transaction to be started must be terminal-related, and associated with the principal facility of the starting task.
      • The principal facility of the task that issues the START command is not a surrogate client virtual terminal.
      • The SYSID option of the START command does not specify the name of a remote region; that is, the remote region on which the transaction is to be started must not be specified explicitly.
    • The requesting region and the TOR, if they are different, are connected by one of the following links:
      • An MRO link
      • An APPC parallel-session link
      • An IPIC link
    • The TOR and the target region are connected by one of the following links:
      • An MRO link.
      • An APPC single- or parallel-session link. If an APPC link is used, at least one of the following conditions must be met:
        1. Terminal-initiated transaction routing has previously taken place over the link.
        2. CICSPlex® SM is being used for routing.
      • An IPIC link.
    • The transaction definition in the requesting region specifies ROUTABLE(YES).
    • If the transaction is to be routed dynamically, the transaction definition in the TOR specifies DYNAMIC(YES).

    For more information about enhanced routing, see Routing transactions invoked by START commands.

  • For a non-terminal-related START request to be eligible for enhanced routing, all of the following conditions must be met:
    • The requesting region and the target region are connected by one of the following links:
      • An MRO link.
      • An APPC single- or parallel-session link. If an APPC link is used, and the distributed routing program is to be called on the target region, at least one of the following conditions must be met:
        1. Terminal-initiated transaction routing has previously taken place over the link.
        2. CICSPlex SM is being used for routing.
      • An IPIC link.
    • The transaction definition in the requesting region specifies ROUTABLE(YES).
    • If the request is to be routed dynamically, the following conditions must be met:
      • The transaction definition in the requesting region specifies DYNAMIC(YES).
      • The SYSID option of the START command does not specify the name of a remote region; that is, the remote region on which the transaction is to be started must not be specified explicitly.

    For more information about enhanced routing, see Routing transactions invoked by START commands.

  • The following types of dynamic transaction routing requests cannot be daisy-chained:
    • Non-terminal-related START requests
    • CICS business transaction services processes and activities