Invoke Transparency Processing for Converted Files
Learn how to invoke transparency processing for converted files with Datacom VSAM Transparency.
JCL Modifications
When processing a VSAM file in native mode, the DD statement for that file is in the following form:
►►─ //ddnameDD DSN=dsname,DISP=SHR ───────────────────────────────►◄
After activating
Datacom VSAM Transparency
, modify the JCL you normally use to execute your batch programs as follows to invoke processing through Datacom VSAM Transparency
. It is not necessary to recompile or relink batch programs.
- Add theSUBSYS=parameter to the native DD statement replacing DSN=aaa,DISP=bbb. The following example includes the two required subparameters forSUBSYS=and two optional parameters.►►─ //ddnameDD SUBSYS=(subsys,'VUTNM=vutnm' ─┬──────────────────┬───────► └─ ,'CLOSE=DEFER' ─┘ ►─┬─────────────────┬─ ) ────────────────────────────────────────────►◄ └─ ,'DDNAME=bbb' ─┘
- ddname
- (Required)Name used in the program being executed to refer to the VSAM cluster or path named by DSN=dsname. If this name is defined byVSAMNM=in the referenced VSAM Interface Table, it is used by the Transparency to identify theDatacom/DBtables to which the VSAM data set has been converted. In this case, do not codeDDNAME=in theSUBSYS=parameter.
- DD
- (Required)Indicates this is a data definition statement.
- SUBSYS=
- (Required)Parameter for identifying the subsystem to be used to process this data set, the VSAM Interface Table in which the data set is defined, and other optional attributes.
- subsys
- (Required)Identifies the subsystem to be used for this data set, where identifier can be any four-character user-defined subsystem orBroadcom-supplied subsystem, CAVT.
- VUTNM=vutnm
- (Required)Identifies the VSAM Interface Table by the name specified during assembly and link-edit. The same vutnm must be specified for allDatacom VSAM Transparencyfiles in a job step.
- DSN=dsname
- (Optional)This parameter is not required byDatacom VSAM Transparency. We recommend that it be removed.
- DISP=
- (Optional)The disposition parameter is not required byDatacom VSAM Transparency. We recommend that it be removed.
- CLOSE=DEFER
- (Optional)Specifies that all program-issued CLOSE requests for a Transparency file are to be deferred until the end of the task. (This deferral allows complete transaction backout in the event of an abend. The program receives the expected successful return codes for the CLOSE, even though they are not actually performed at that time.)See How Datacom VSAM Transparency Works with Batch Processing for descriptions of CLOSE processing under normal and abnormal conditions.
- DDNAME=bbb
- (Optional)Indicates that bbb is to override the DDNAME specified by ddname at the beginning of the statement. See Example of DDNAME Substitution. Code this parameter only ifVSAMNM=bbbis defined in the specified VSAM Interface Table for the data set to be processed.
- For each job step that is to useDatacom VSAM Transparency, add a DD statement that names the model VSAM file defined during installation. This DD statement must be defined as follows:►►─ //DB$VSAMT DD DSN=aaa.VTMODEL,DISP=SHR ───────────────────────►◄
- DB$VSAMT
- ddname for theDatacom VSAM Transparencymodel file.
- DD
- Identifies statement as a data definition statement.
- DSN=aaa.VTMODEL
- Identifies the model native VSAM file, whereaaarepresents the high-level nodes assigned duringDatacom VSAM Transparencyinstallation or upgrade.
- DISP=SHR
- Disposition is shared.
Example of Required Modifications
The following statements appear in the INSTJCL member BGIVP01 for installation verification. They show modifications made to the two DD statements that name the VSAM base cluster and path and the added statement that names the model VSAM file:
//CUSTMR DD SUBSYS=(CAVT,'VUTNM=DVVUTPR') //CUSTMR1 DD SUBSYS=(CAVT,'VUTNM=DVVUTPR') //DB$VSAMT DD DISP=SHR,DSN=CAI.DATACOM.VTMODEL
Example of DDNAME Substitution
The following examples demonstrate how to override the program-issued DDNAME with the DDNAME defined in the VIT.
In the DD statement of the JCL, you identify the VSAM Interface Table which describes the converted VSAM file to process and the data definition name of the converted VSAM file. Generally, the modified statement is in the following form, where ddname is the data definition name of the file to process and vutnm is the name of the VSAM Interface Table.
//ddname DD SUBSYS=(CAVT,'VUTNM=vutnm')
The data definition name is defined in the VIT by the parameter,
VSAMNM=
. It is defined in the JCL at the beginning of the DD statement or with the SUBSYS=
subparameter, DDNAME=
. The DDNAME=
subparameter of the SUBSYS=
parameter in the JCL, permits you to override the DDNAME which begins the DD statement with the DDNAME as it is defined by VSAMNM=
in the referenced VSAM Interface Table. This feature is useful if you have numerous programs which reference different files, but which use the same DDNAME for the file, for example, SORTIN. The following statement shows how to replace the DDNAME which is required when doing native processing (SORTIN) with the DDNAME defined to the referenced VSAM Interface Table (CUSTMR).
//SORTIN DD SUBSYS=(CAVT,'VUTNM=vutnm','DDNAME=CUSTMR')
It is also useful when you have separate test and production versions of your data, for example, PMASTER and TMASTER, and your program is set up to process the production version, PMASTER. The JCL prior to modification follows:
//PMASTER DD SUBSYS=(CAVT,'VUTNM=vutnm')
The following modified JCL allows you to process the test version, TMASTER.
//PMASTER DD SUBSYS=(CAVT,'VUTNM=vutnm','DDNAME=TMASTER')
In this example, the VSAM Interface Table referenced by VUTNM= could include two
DBVUFIL
macros with the following specifications:
- VSAMNM=PMASTER,DBFILE=MAS,DBID=100
- VSAMNM=TMASTER,DBFILE=MAS,DBID=200
Here PMASTER and TMASTER would actually reference the same VSAM data set. The names of the converted files (MAS) are identical, although they are defined to separate databases.