Allocating External Files

Allocating Generation Data Sets

A generation data set (or generation) is a version of a z/OS data set that is stored as a member of a generation data group. These generations are supported by z/OS; they differ from the generation data sets supported by SAS. For detailed information about z/OS generations, see your IBM documentation. For information about SAS generation data sets, see the SAS Language Reference: Concepts. See also Allocating a Multivolume Generation Data Group.

Both standard external files and SAS libraries can be stored and managed as generation data groups. The following sections describe the various methods of allocating new and existing generations.

Allocating a New Generation of a Generation Data Group

To allocate a new generation of a generation data group, use one of the following methods:

In a JCL DD statement, you can specify either the relative form of the data set name or the absolute form.
Relative form:
```
//DD1  DD DSN=PROD.GDG(+1),DISP=(NEW,CATLG)
```
Absolute form:
```
//DD1  DD DSN=PROD.GDG.G0008V00,DISP=(NEW,CATLG)
```
In a SAS FILENAME statement or FILENAME function (for external files) or in a TSO ALLOCATE command, you must specify the absolute form of the data set name.
FILENAME statement:
```
filename dd1 'prod.gdg.g0008v00' disp=(new,catlg);
```
TSO ALLOCATE command:
```
alloc fi(dd1) da('prod.gdg.g0008v00') new
```

Allocating an Existing Generation of a Generation Data Group

To access an existing generation of a generation data group, you can use either the relative form of the data set name or the absolute form in a FILENAME statement FILENAME function, JCL DD statement, or TSO ALLOCATE command.

Relative form:

FILENAME statement:

filename gdgds 'my.gdg.data(-1)';

JCL DD statement:

//DD1    DD DSN=PROD.GDG(-1),DISP=SHR

TSO ALLOCATE command:

alloc fi(dd1) da('prod.gdg(-1)') shr

Absolute form:

FILENAME statement:

filename gdgds 'my.gdg.data.g0008v01';

JCL DD statement:

//DD1    DD DSN=PROD.GDG.G0008V01,DISP=SHR

TSO ALLOCATE command:

alloc fi(dd1) da('prod.gdg.g0008v01') shr

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