Data tables sample exit program: DFH$DTLC
DFH$DTLC is a sample XDTLC global user exit program. It demonstrates the use of the XDTLC user exit for shared data tables. Copybook DFHXDTDS defines the data tables user exit parameter list that is used in the sample.
About DFH$DTLC - Sample XDTLC global user exit program
This program is intended to demonstrate the use of the data tables user exit XDTLC. The program rejects a data table if its load completes with errors. It will be invoked, if enabled, when the load of a data table has completed.
This global user exit program is intended for use in the following situations:
- On CICS systems that have only the original data table support (that is, before shared data tables)
- On CICS systems that have shared data table support
- On CICS systems that have shared date table support and coupling facility data table support
Flags are passed in the data tables parameter list, which can be used to determine whether the exit has been invoked from a system that supports shared data tables or coupling facility data tables.
The program will issue a user trace entry if tracing is enabled. You can check the setting of the load completion indicator. If it shows that loading failed to complete successfully, the exit program will set a return code that rejects the table by requesting that it be closed.
The trace flag passed to the exit is set ON if File Control (FC) level 1 tracing is enabled.
Note: This program is intended only to demonstrate the use of the data tables user exit XDTLC and to
show the sort of information that can be obtained from the exit parameter list. The sample program
should be tailored before it is used in a production environment.
Prerequisites for DFH$DTLC
- DFH$DTLC, or an exit program that is based on this sample, must be defined on the CSD as a program with DATALOCATION(ANY).
- DFH$DTLC requires the DFHXDTDS copybook to be available at assembly time. DFHXDTDS is shown in Communicating between CICS and shared data table exit programs.
TITLE 'DFH$DTLC - Sample XDTLC Global User Exit Program'
***********************************************************************
* *
* MODULE NAME = DFH$DTLC *
* *
* DESCRIPTIVE NAME = %PRODUCT Data Tables Sample XDTLC Exit *
* *
* STATUS = %JUP0 *
* *
* FUNCTION = *
* Sample Global User Exit Program to run at the XDTLC exit *
* *
* The program rejects a data table if its load did not complete OK. *
* *
* ------------------------------------------------------------------- *
* NOTE that this program is only intended to DEMONSTRATE the use *
* of the data tables user exit XDTLC, and to show the sort of *
* information which can be obtained from the exit parameter list. *
* IT SHOULD BE TAILORED BEFORE BEING USED IN A PRODUCTION ENVIRONMENT *
* If this program is modified to accept a load that has failed *
* or reject a load that has been successful, it is the *
* responsibility of the program to issue a message indicating *
* what has happened. Any message output by CICS File Control will *
* only reflect what happened before modification of return codes *
* by the exit program. *
* ------------------------------------------------------------------- *
* *
* This global user exit program will be invoked, if enabled, when *
* the load of a data table has completed. *
* *
* The program is intended for use in the following situations : *
* *
* (1) on CICS systems that have only the original data table *
* support (ie.before shared data tables) *
* (2) on CICS systems that have shared data table support *
* (3) on CICS systems that have shared date table support AND *
* coupling facility data table support *
* *
* Flags are passed in the data tables parameter list which may *
* be used to determine whether the exit has been invoked from *
* a system which supports shared data tables or coupling facility *
* data tables. *
* *
* The program will issue a user trace entry if tracing is enabled, *
* then check the setting of the load completion indicator. *
* If this shows that loading failed to complete successfully, then ** the exit program will set a return code that rejects the table *
* by requesting that it be closed. *
* *
* The trace flag passed to the exit is set ON if File Control (FC) *
* level 1 tracing is enabled. *
* *
* NOTES : *
* DEPENDENCIES = S/390 *
* DFH$DTLC, or an exit program which is based on this *
* sample, must be defined on the CSD as a program *
* (with DATALOCATION(ANY)). *
* RESTRICTIONS = *
* This program is designed to run on CICS/ESA 3.3 or later *
* release. It requires the DFHXDTDS copybook to be *
* available at assembly time. *
* REGISTER CONVENTIONS = see code *
* MODULE TYPE = Executable *
* PROCESSOR = Assembler *
* ATTRIBUTES = Read only, AMODE 31, RMODE ANY *
* *
*---------------------------------------------------------------------*
* *
* ENTRY POINT = DFH$DTLC *
* *
* PURPOSE = *
* Described above *
* *
* LINKAGE = *
* Called by the user exit handler *
* *
* INPUT = *
* Standard user exit parameter list DFHUEPAR, *
* addressed by R1 and containing a pointer to the *
* Data Tables parameter list *
* *
* OUTPUT = *
* Return code placed in R15 *
* *
* EXIT-NORMAL = *
* Return code in R15 can be *
* UERCDTOK = accept table *
* UERCDTCL = reject table (close it) *
* *
* EXIT-ERROR = *
* None *
* *
*---------------------------------------------------------------------*
* *
* EXTERNAL REFERENCES : *
* ROUTINES = None *
* DATA AREAS = None *
* CONTROL BLOCKS = ** User Exit Parameter list for XDTLC: DFHUEPAR *
* Data Tables User Exit Parameter List: DT_UE_PLIST *
* GLOBAL VARIABLES = None *
* *
* TABLES = None *
* *
* MACROS = *
* DFHUEXIT to generate the standard user exit parameter list *
* with the extensions for the XDTLC exit point *
* DFHUEXIT to declare the XPI (exit programming interface) *
* DFHTRPTX XPI call to issue a user trace entry *
* *
*---------------------------------------------------------------------*
* *
* DESCRIPTION of the program structure: *
* *
* 1) Standard entry code for a global user exit that uses the XPI: *
* The program sets up any definitions required, then saves *
* the caller's registers, establishes addressability, and *
* addresses the parameter lists. *
* 2) Tracing (only executed if FC level 1 tracing is enabled): *
* The program tests whether it was invoked from shared data *
* table code. If so, it issues a user trace point X'0126' *
* including fields from the data table parameter list which *
* are only supplied by shared data table support or *
* coupling facility data table support. If not, it *
* issues a X'0116' trace point, containing parameters which *
* are supplied by any level of data table support. *
* 3) Choosing whether to accept the table: *
* The program tests the return code from the load. If the *
* load failed to complete, then it sets UERCDTCL in R15, *
* which requests that the table should be closed. If the *
* load completed successfully, then it sets UERCDTOK in R15 *
* to keep the table open. *
* 4) Standard exit code for a global user exit that uses the XPI: *
* Restore users registers, and return to the address that was *
* in R14 when the exit program was called. *
*---------------------------------------------------------------------*
* *
***********************************************************************
EJECT , DFHUEXIT TYPE=EP,ID=XDTLC standard UE parameters for XDTLC
DFHUEXIT TYPE=XPIENV exit programming interface (XPI)
EJECT ,
COPY DFHXDTDS Additional data table UE params
EJECT ,
COPY DFHTRPTY Trace definitions
EJECT ,
***********************************************************************
* Register usage : *
* R0 - *
* R1 - address of DFHUEPAR on input, and used by XPI calls *
* R2 - address of standard user exit plist, DFHUEPAR *
* R3 - *
* R4 - address of source data set name *
* R5 - address of storage for XPI parameters *
* R6 - address of data tables parameter list, DT_UE_PLIST *
* R7 - address of the trace flag, UEPTRACE *
* R8 - address of data table name *
* R9 - address of loading completion indicator, UEPDTORC *
* R10- *
* R11- base register *
* R12- address of data table flags byte, UEPDTFLG *
* R13- address of kernel stack before XPI calls *
* R14- used by XPI calls *
* R15- return code, and used by XPI calls *
* (The register equates are declared by the DFHUEXIT call above) *
***********************************************************************
SPACE 2
DFH$DTLC CSECT
DFH$DTLC AMODE 31
DFH$DTLC RMODE ANY
STM R14,R12,12(R13) Save caller's registers
LR R11,R15 Establish base
USING DFH$DTLC,R11
LR R2,R1 Address standard parameters
USING DFHUEPAR,R2
L R6,UEPDTPL Address data table parameters
USING DT_UE_PLIST,R6
SPACE 1
LA R8,UEPDTNAM Address data table name
LA R9,UEPDTORC Address load return code
***********************************************************************
* Issue Trace (if tracing is enabled) *
***********************************************************************
L R7,UEPTRACE Get trace flag address
TM 0(R7),UEPTRON Is trace on?
BZ CHOOSE Skip tracing if not
***********************************************************************
* Test whether the exit was invoked from shared data tables support *
* or coupling facility data table support *
*********************************************************************** TM UEPDTFLG,UEPDTSDT Were we invoked from SDT?
BO SDTCFDT Branch if yes
TM UEPDTFLG,UEPDTCFT or coupling facility data tables?
BZ NOTSDT Branch to non-SDT and non coupling
* facility data table code if not
EJECT ,
SDTCFDT DS 0H
***********************************************************************
* Exit has been invoked from SDT or coupling facility data *
* tables *
***********************************************************************
L R5,UEPXSTOR Set up XPI trace call
USING DFHTRPT_ARG,R5
L R13,UEPSTACK
***********************************************************************
* Trace data table name, load return code, source dsname, and flags. *
* The last two fields are only meaningful for SDT support or *
* coupling facility data table support.
***********************************************************************
LA R4,UEPDTDSN Get source data set name
LA R12,UEPDTFLG Get data table flags
DFHTRPTX CALL, *
CLEAR, *
IN, *
FUNCTION(TRACE_PUT), *
POINT_ID(LCTRACE2), *
DATA1((R8),8), *
DATA2((R9),1), *
DATA3((R4),UEPDTDSL), *
DATA4((R12),1), *
OUT, *
RESPONSE(*), *
REASON(*)
B CHOOSE Go and test if load completed OK
EJECT ,
***********************************************************************
* Exit has not been invoked from SDT or coupling facility *
* data tables *
***********************************************************************
NOTSDT L R5,UEPXSTOR Set up XPI trace call
USING DFHTRPT_ARG,R5
L R13,UEPSTACK
***********************************************************************
* Trace data table name and load return code *
***********************************************************************
DFHTRPTX CALL, *
CLEAR, *
IN, *
FUNCTION(TRACE_PUT), *
POINT_ID(LCTRACE1), *
DATA1((R8),8), * DATA2((R9),1), *
OUT, *
RESPONSE(*), *
REASON(*)
EJECT ,
***********************************************************************
* If load completed successfully, then keep table open *
* If not, ask for it to be closed *
***********************************************************************
CHOOSE DS 0H
CLI 0(R9),UEPDTLFL Did load fail?
BNE LOADOK
LA R15,UERCDTCL Set RC for table to be closed
B GLUEND
LOADOK LA R15,UERCDTOK Set RC to keep table
SPACE 3
GLUEND DS 0H Standard GLUE exit code
L R13,UEPEPSA
L R14,12(R13)
LM R0,R12,20(R13)
BR R14
SPACE 2
***********************************************************************
* Constant Declarations *
***********************************************************************
LCTRACE1 DC XL2'116'
LCTRACE2 DC XL2'126'
SPACE 1
END DFH$DTLCExtending DFH$DTLC
This program can be modified to accept a load that has failed, or reject a load that has been successful. Note that it is the responsibility of the program to issue a message indicating what has happened. Any message output by CICS File Control will only reflect what happened before modification of return codes by the exit program.