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Notes:
1. An attempt to start CEDA from an application program by an EXEC CICS
START command must fail. This is because CEDA’s first action is to request
input from its associated terminal, whereas an automatically initiated transaction
must first send data to the terminal.
An attempt to start CEDA under CECI by an EXEC CICS START command fails
for similar reasons.
2. The RDO command passed in address 1 of the CEDAPARM parameter list
must be valid. (For example, spelling errors such as PRORGAM for PROGRAM
are not corrected automatically when you use the programmable interface.)
3. You cannot use the programmable interface to change the values of CEDA
keywords that are obsolete in this release of CICS, but which are retained for
compatibility with earlier releases. That is, the interface does not support
compatibility mode
.
4. CEDA issues various syncpoints as part of its processing. Therefore, when your
program links to DFHEDAP the current unit of work (UOW) of the transaction is
completed. This may result in problems if, for example, there are outstanding
browse operations against VSAM datasets.
Use of the programmable interface
Remember that you can use the offline utility program, DFHCSDUP, to examine and
amend CSD files; and that DFHCSDUP can be invoked from a user program,
running either in batch mode or under TSO. (See “Chapter 30. User programs for
the system definition utility program (DFHCSDUP)” on page 741.)
Using DFHCSDUP is the recommended method for updating CSD files in bulk.
You should only use the interface described in this chapter where the required
function includes the INSTALL command, which is not available from DFHCSDUP.
Using DFHEDAP in a DTP environment
The LINK DFHEDAP function is intended to be used in a single environment. It is
not supported within a distributed transaction programming (DTP)
environment—using it such an environment can result in abends.
In a DTP environment, CICS may attempt to propagate SYNCPOINT and
SYNCPOINT ROLLBACK requests across sessions to other systems. These
requests are issued by CEDA modules that are invoked by the use of LINK
DFHEDAP. Note that the issuing of SYNCPOINT ROLLBACK means that LINK
DFHEDAP cannot be used in a DTP environment that owns LU6.1 links.
Generally, a session should be in SEND state to initiate a SYNCPOINT, but the
session may not remain in SEND state once a LINK DFHEDAP command is issued.
(For information about valid commands and states, see the
CICS Distributed
Transaction Programming Guide
. This book also explains the APPC architecture
rules on a session’s state after SYNCPOINT and SYNCPOINT ROLLBACK
requests are made.)
The code invoked by LINK DFHEDAP can result in wrong sequence of commands.
For example, if the code invoked by DFHEDAP issues a SYNCPOINT ROLLBACK
the programmable interface to CEDA
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CICS TS for OS/390: CICS Customization Guide