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The COVR transaction
To ensure that CICS reconnects to VTAM in the event of a VTAM abend, CICS
keeps retrying the OPEN VTAM ACB using a time-delay mechanism via the
non-terminal transaction COVR.
After CICS has completed clean-up following the VTAM failure, it invokes the
CICS open VTAM retry (COVR) transaction. The COVR transaction invokes the
terminal control open VTAM retry program, DFHZCOVR, which performs an
OPEN VTAM retry loop with a 5-second wait. CICS issues a DFHZC0200 message
every minute, while the open is unsuccessful, and each attempt is recorded on the
CSNE transient data queue. After ten minutes, CICS issues a DFHZC0201 message
and terminates the transaction. If CICS shutdown is initiated while the transaction
is running, CICS issues a DFHZC0201 message and terminates the transaction.
You cannot run the COVR transaction from a terminal. If you invoke COVR from a
terminal, it abends with an AZCU transaction abend.
Messages associated with automatic restart
There are some CICS messages for ARM support, which CICS can issue during
startup if problems are encountered when CICS tries to connect to ARM.
The message numbers are:
DFHKE0401 DFHKE0407
DFHKE0402 DFHKE0408
DFHKE0403 DFHKE0410
DFHKE0404 DFHKE0411
DFHKE0405 DFHZC0200
DFHKE0406 DFHZC0201
For the text of these messages, see CICS Messages and Codes.
Automatic restart of CICS data-sharing servers
All three types of CICS data-sharing server—temporary storage, coupling facility
data tables, and named counters—support automatic restart using the services of
automatic restart manager.
The servers also have the ability to wait during start-up, using an event
notification facility (ENF) exit, for the coupling facility structure to become
available if the initial connection attempt fails.
Server ARM processing
During initialization, a data-sharing server unconditionally registers with ARM,
except when starting up for unload or reload. A server does not start if registration
fails, with return code 8 or above.
If a server encounters an unrecoverable problem with the coupling facility
connection, consisting either of lost connectivity or a structure failure, it cancels
itself using the server command CANCEL RESTART=YES. This terminates the existing
connection, closes the server and its old job, and starts a new instance of the server
job.
Chapter 7. Automatic restart management 71