Accessing a data set with DFSMStvs

To enable DFSMStvs processing, begin by requesting RLS processing in either of these ways:

Specify the MACRF=RLS parameter in the ACB macro.
Specify the RLS parameter in the JCL.

In addition, do either of these tasks:

Open a recoverable data set for output from a non-CICS batch job.
The data set is recoverable if its LOG parameter is specified as UNDO or ALL.
Request the CRE read-integrity option in the JCL or through the ACB.

VSAM RLS enables batch jobs to access recoverable data sets in RLS mode, but only for reading; batch jobs cannot write to these data sets in RLS mode. With DFSMStvs, batch jobs that support two-phase commit and backout protocols are able to read and write to recoverable data sets. Concurrently, CICS® is processing those same data sets.

For DFSMStvs, a commit protocol application includes programs that can be invoked from a batch job and that use RRS to support two-phase commit and backout. To use DFSMStvs, batch jobs must support and understand sync points (commit and backout) and use RRS services.

Table 1 shows the type of open resulting from the parameters specified for a VSAM data set opened by a batch job (non-CICS). The left column shows the type of data set and type of open. Column headings indicate the RLS option specified.

Table 1. Opening recoverable and nonrecoverable VSAM data sets from batch jobs
Data set type and type of open	NRI	CR	CRE
Recoverable open for input	RLS	RLS	DFSMStvs
Recoverable open for output	DFSMStvs	DFSMStvs	DFSMStvs
Nonrecoverable open for input	RLS	RLS	DFSMStvs
Nonrecoverable open for output	RLS	RLS	DFSMStvs

The results of opening different types of VSAM data sets with different read integrity options (NRI, CR, or CRE) depend on whether the batch job opens the data set for input or output, as follows:

If you open a recoverable data set for output from a batch job (non-CICS) and you specify RLS with any option (NRI, CR, or CRE), you get a DFSMStvs open.
If you attempt to open a recoverable data set for output from a batch job (non-CICS) and you do not specify RLS, the open will fail (unless the open attempt is during your batch window processing and you have disabled access by CICS to the data set).
If you open a recoverable data set for input from a batch job (non-CICS) and you specify RLS with any option (NRI, CR, or CRE), you get an RLS open.
If you open a recoverable data set for input from a batch job (non-CICS) and you do not specify RLS, you get whatever type of open you requested: NSR, LSR, or GSR (provided share option 2 is in effect).
If you open a nonrecoverable data set for output from a batch job (non-CICS) and you specify RLS as either NRI or CR, you get an RLS open.
If you open a nonrecoverable data set for output from a batch job (non-CICS) and you specify RLS as CRE, you get a DFSMStvs open.
If you open a nonrecoverable data set for input from a batch job (non-CICS) and you specify RLS as either NRI or CR, you get an RLS open.
If you open a nonrecoverable data set for input from a batch job (non-CICS) and you specify RLS as CRE, you get a DFSMStvs open.
If you open a nonrecoverable data set for output from a batch job (non-CICS) and you do not specify RLS, you get whatever type of open you requested: NSR, LSR, or GSR (provided share option 2 is in effect).
If you open a nonrecoverable data set for input from a batch job (non-CICS) and you do not specify RLS, you get whatever type of open you requested: NSR, LSR, or GSR (provided share option 2 is in effect).