Design overview

Figure 107 shows the relationships between the components of AP domain termination.

Figure 107. AP domain termination program interfaces
 This is a technical drawing showing the components of AP domain termination and their relationship to each other.
Notes:
  1. When a PERFORM SHUTDOWN or PERFORM TAKEOVER command is used, either on the CEMT transaction or by an EXEC CICS® command, the DFHEIPSH program:
    • Loads the transaction list table (XLT) and program list table (PLT) from the DFHRPL DD concatenation
    • Transfers control to DFHSTP by means of a DFHPGXE PREPARE_XCTL_EXEC domain call.
  2. For an immediate shutdown, statistics are collected at the step described by 1. Following this, the resource managers and the subsystem interface are terminated; no load of tables, terminal quiescing, or execution of programs specified in the PLT occurs, that is to say the steps described in notes ***, 2, 3, and 4 are not performed on an immediate shutdown. Also, CICS files are not closed during step 5 on an immediate shutdown.

  3. Terminal activity is quiesced via an indicator in the CSA. This tells terminal control not to attach any transactions other than those specified in the XLT and those specifying SHUTDOWN(ENABLED) in their associated TRANSACTION resource definitions. The termination task logically disconnects itself from the physical terminal to allow other activity on that terminal.
  4. The termination task allows all other tasks (except any journal tasks) to complete before linking to the first program specified in the first portion of the PLT.
  5. When all programs in the first portion of the PLT have executed, terminal activity is quiesced completely, using bit CSATQIM in CSASSI2 in the CSA. If monitoring is running, it is stopped. The ICE and AID chains are broken (addresses saved in the TWA), the IRC session is quiesced, and the programs specified in the second portion of the PLT are executed.
  6. All open files managed by CICS file control are closed by the file control shutdown program, DFHFCSD; temporary-storage control, DFHTSP is requested to output its buffer; and a keypoint is taken by the warm keypoint program, DFHWKP.
  7. Control is returned to the operating system, with or without a dump (depending upon the parameters specified in the shutdown request causing termination).

    For the high-performance option (HPO), the service request block (SRB) in the system queue area (SQA) is freed by using a CICS SVC (DFHCSVC).

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