SAS Companion for the OS/390 Environment

Using the V8TAPE Engine

The V6TAPE engine is functionally equivalent to the V8TAPE engine. Information in this section that applies to V8TAPE also applies to V6TAPE.

When to Use This Engine

Use the V8TAPE engine to create sequential-format SAS data libraries either on disk or on tape, and to access files in sequential data libraries. The primary purpose of this engine is to enable you to back up Version 8 SAS data sets, catalogs, or whole data libraries. The V8TAPE engine makes it possible to back up applications that contain both SAS data sets and SAS catalogs. The V8TAPE engine also enables you to transport a tape-format library to another OS/390 or CMS system via tape or shared DASD. Finally, you can use this engine to create a multivolume sequential-format SAS data library on tape or disk.

In contrast to the V8 engine, V8TAPE has the following limitations:

It does not support indexing nor compression of observations.
Because a V8TAPE SAS data library does not contain a directory, SAS cannot access an individual data set directly. It must read through all preceding SAS data sets in order to reach a requested data set. Direct access to individual observations (using the POINT= or KEY= options in the SET or MODIFY statements) also is not supported.
In a single DATA step or PROC step, you can use only one SAS data set from a particular sequential SAS data library.

Unlike disk-format libraries, sequential libraries are always closed at step boundaries.

Note: Information in this section also applies to the V6TAPE engine. [cautionend]

How to Select the V8TAPE Engine

There are three ways to select this engine:

Specify V8TAPE as the value of the engine argument in the LIBNAME statement or LIBNAME function.
Note: Use TAPE as the engine name if you write programs that create new SAS data libraries and you want to create the data libraries in the latest available format. In SAS Version 8, TAPE is an alias for V8TAPE, and it will be an alias for newer sequential engines in subsequent releases.
For existing V8TAPE SAS data libraries on tape, specify no value for engine in the LIBNAME statement or LIBNAME function. This engine is selected automatically if you do not provide a value for the engine argument and you are allocating the library internally. This engine is also selected automatically if you omit the LIBNAME statement or function and allocate the library externally.
Set the value of the SEQENGINE= system option to SASV8SEQ. The DCB attributes of the allocated data set must indicate a sequential format SAS data library.

DCB Attributes for Direct Access Bound Libraries with the V8TAPE Engine

The physical file label contains DCB information which describes the data library's characteristics. The operating environment writes the DCB information when it creates the library, using either values that are supplied by the user, or the values of several SAS system options. Both the SAS System and OS/390 utility programs use this DCB information during processing.

See DCB Attribute Options for more information about DCB attributes.

External Allocation: V8TAPE Engine

If you use a JCL DD statement or a TSO ALLOCATE command to allocate a new V8TAPE data library on disk or on tape, and if you choose to specify DCB attributes, then you must specify the following DCB attributes:

DSORG=PS
RECFM=U
BLKSIZE=value, where value is up to the maximum for your device type.

If you do not specify DCB attributes for a new V8TAPE SAS data library, then SAS supplies the above DCB attributes whenever the V8TAPE engine has been either explicitly or implicitly assigned. (See How to Select the V8TAPE Engine and How SAS Assigns an Engine When No Engine Is Specified for details about how engines are assigned.)

Note: In order to use the TSO ALLOCATE command or LIBNAME statement to allocate a data set on tape, your user ID must have MOUNT authority. See your system administrator for details. [cautionend]

Internal Allocation: V8TAPE Engine

If you use the LIBNAME statement or LIBNAME function to allocate a new V8TAPE data library on disk or on tape, SAS supplies the following DCB attributes for you:

DSORG=PS
RECFM=U

In addition, if no block size is specified when a SAS data library is physically opened for the first time, SAS uses the value of the BLKSIZE= system option. If that value is 0, then SAS uses the BLKSIZE(device-type)= system option. If the value of BLKSIZE(device-type)= is 0, SAS uses the largest block size that the device supports.

Note: If the SAS system option BLKALLOC is in effect, then SAS assigns BLKSIZE= and LRECL= values when the SAS data library is allocated. If NOBLKALLOC is in effect, then SAS assigns BLKSIZE= and LRECL= values when the library is first accessed. [cautionend]

Engine/Host Options for Direct Access Bound Libraries with the V8TAPE Engine

The engine/host options that you can supply in the LIBNAME statement or LIBNAME function correspond to the JCL or TSO parameters that you would specify if you allocated the SAS data library externally. For bound libraries using the V8TAPE engine, you can specify any of the engine/host options shown in Overview of the V8 and V8TAPE Engines. (For more information about these options and their values, see the description of engine/host options under LIBNAME.) Or you can accept the default values that are derived from the corresponding SAS system options, as follows:

If you do not specify a value for DISP=, the default for existing data sets is DISP=(OLD,KEEP,KEEP). For new data sets, the default is DISP=(NEW,CATLG,DELETE). If you specify only DISP=NEW and omit the normal disposition parameter, the following defaults occur:
- If you are allocating the library with a LIBNAME statement, a LIBNAME function, or with a TSO ALLOCATE command, normal disposition defaults to CATLG.
- If you are allocating the library with a JCL DD statement, normal disposition defaults to DELETE for new data sets.
In an interactive environment, when you use a LIBNAME statement or LIBNAME function to allocate a data library that does not exist and you do not specify a value for DISP=, one of the following actions occurs:
- If the SAS system option FILEPROMPT is in effect (the default), then a requestor window asks whether you want to create the physical file. If you reply Yes, you are asked whether you want to catalog the data set when it is deallocated, or to delete it.
- If the SAS system option NOFILEPROMPT is in effect, an error message is written to the SAS log.
If you do not specify values for the SPACE= parameters, SAS uses the current values of the SAS system options FILEUNIT=, FILESPPRI=, and FILESPSEC=. The defaults are SPACE=(CYL,(1,1)).
If you do not specify a value for VOLSER=, SAS uses the current value of the SAS system option FILEVOL=, if a value for FILEVOL= has been specified at your site.
If you do not specify a value for UNIT=, SAS uses the current value of the SAS system option FILEDEV=. The default is SYSDA.

Note: The default values shown are those that are supplied by SAS. Your SAS system administrator may have changed the default values for your site. [cautionend]

For temporary data libraries, you do not need to specify any options, but you can override any of the default values.

CONTENTS Procedure Output

The PROC CONTENTS output in PROC CONTENTS Output Generated by the V8TAPE Engine shows information that is generated by the V8TAPE engine.

PROC CONTENTS Output Generated by the V8TAPE Engine

The SAS System The CONTENTS Procedure Data Set Name: SEQ.ORANGES Observations: . Member Type: DATA Variables: 5 Engine: V8TAPE Indexes: 0 Created: 14:48 Tuesday, March 5, 1999 Observation Length: 40 Last Modified: . Deleted Observations: 0 Protection: Compressed: NO Data Set Type: Sorted: NO Label: -----Engine/Host Dependent Information----- Data Set Page Size: 32000 Physical Name: USERID.OS390.SEQ Release Created: 8.0 Created by: USERID -----Alphabetic List of Variables and Attributes----- # Variable Type Len Pos ----------------------------------- 2 FLAVOR Num 8 8 4 LOOKS Num 8 24 3 TEXTURE Num 8 16 5 TOTAL Num 8 32 1 VARIETY Char 8 0

In the output example above, SAS version information appears in the Engine and Release created fields.

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