11.01.2013 Views

ABCs of z/OS System Programming Volume 3 - IBM Redbooks

ABCs of z/OS System Programming Volume 3 - IBM Redbooks

ABCs of z/OS System Programming Volume 3 - IBM Redbooks

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

7.29 Accessing a data set with DFSMStvs<br />

This table lists the type <strong>of</strong> OPEN resulting from the<br />

parameters specified<br />

Left side shows the type <strong>of</strong> data set and type <strong>of</strong> open<br />

Column headings indicate the RLS option specified<br />

Data Set Type &<br />

Type <strong>of</strong> OPEN<br />

Recoverable<br />

Open for Input<br />

Recoverable<br />

Open for Output<br />

Non-recoverable<br />

Open for Input<br />

Non-recoverable<br />

Open for Output<br />

Figure 7-38 Accessing a data set with DFSMStvs<br />

NRI CR CRE<br />

VSAM RLS VSAM RLS DFSMStvs<br />

DFSMStvs DFSMStvs DFSMStvs<br />

VSAM RLS VSAM RLS DFSMStvs<br />

VSAM RLS VSAM RLS DFSMStvs<br />

Data set access with DFSMStvs<br />

In 7.9, “VSAM RLS locking” on page 390 we discuss the MACRF options NRI, CR, and CRE.<br />

CRE gives DFSMStvs access to VSAM data sets open for input or output. CR or NRI gives<br />

DFSMStvs access to VSAM recoverable data sets only for output.<br />

You can modify an application to use DFSMStvs by specifying RLS in the JCL or the ACB and<br />

having the application access a recoverable data set using either open for input with CRE or<br />

open for output from a batch job.<br />

The table in Figure 7-38 shows in which cases DFSMStvs is invoked.<br />

DFSMStvs is always invoked if:<br />

► RLS and CRE is specified in the JCL or MACRF parameter <strong>of</strong> the ACB macro<br />

CRE is also known as repeatable read.<br />

► RLS is specified in the JCL or MACRF parameter <strong>of</strong> the ACB macro and the data set is<br />

recoverable and it is opened for output (update processing)<br />

This allows DFSMStvs to provide the necessary transactional recovery for the data set.<br />

Chapter 7. DFSMS Transactional VSAM Services 429

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!