- 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.
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.
- 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.
- 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.
- 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.
- 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.
- 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).