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Chapter 19. Writing a CICS–DBCTL interface status program
Considerations common to all user-replaceable programs
Note that the comments contained in Chapter 5, “General notes about
user-replaceable programs,” on page 435 apply to this chapter.
The CICS–DBCTL interface status program DFHDBUEX is a user-replaceable
program forming part of the support for the CICS–DBCTL interface. It is designed to
invoke user-supplied code whenever CICS successfully connects to or disconnects
from DBCTL. It runs in a CICS application environment and is driven at specific
points to allow you to enable and disable your CICS-DL/I transactions when the
CICS–DBCTL interface initializes or terminates.
DFHDBUEX is invoked in the following case for the ENABLE command:
v CICS has connected to DBCTL successfully. This occurs after a connection
request has been issued from CICS to DBCTL. The control exit (DFHDBCTX) is
invoked by the database resource adapter (DRA) for
7
‘initialization complete’. The
control exit posts the control transaction (CDBO). The control program
(DFHDBCT) then invokes DFHDBUEX.
DFHDBUEX is invoked in the following cases for the DISABLE command:
v A request has been issued to disconnect from DBCTL. The CICS–DBCTL menu
program (DFHDBME) starts the disconnection transaction (CDBT) to disconnect
from DBCTL. The disconnection program (DFHDBDSC) invokes DFHDBUEX
before issuing the interface termination request to the adapter.
v The control transaction (CDBO) has been notified of one of the following events:
– A checkpoint freeze request to DBCTL
– DRA abnormal termination
– DBCTL abnormal termination.
In each of these cases, the control program (DFHDBCT) invokes DFHDBUEX.
Input to DFHDBUEX is by means of a communication area addressed by
DFHEICAP. The layout of the communication area is shown in Figure 66.
The parameter list contains the following information:
DBUREQT
Request Type. The function code has one of the following values:
DBUCONN (X'01')
Connected
7. The interface that enables DBCTL databases to be accessed from CICS.
DBUSHEAD DS OCL4 Standard Header
DBUREQT DS CL1 Function Code
DBUCOMP DS CL2 Component Code Always "DB"
DBURESV DS CL1 Reserved
DBUREAS DS CL1 Reason for disconnection
DBUSUFF DS CL2 DRA startup table suffix
DBUDBCTL DS CL4 DBCTL identifier
Figure 66. The DFHDBUEX communication area
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