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SAS Companion for the OS/390 Environment

Using V8 Engines

A V8 data library is a physical file that is formatted to be compatible with the V8 engine. The V8 engine format enables you to access any of the SAS data sets in the library directly, without searching through other SAS data sets. You can read or write more than one SAS data set in a disk-format data library in a single DATA step. Note that preceding does not apply to SAS HFS data libraries stored in UNIX System Services directories.

When to Use This Engine

You use the V8 engine to create SAS data libraries on disk and to read from, write to, or update those libraries. The V8 engine also enables you to index and compress observations. For more information about indexes, see SAS Language Reference: Dictionary. For more information about compressing observations, see SAS Language Reference: Dictionary and Determine whether you should compress your data.

The V8 engine is the default engine for SAS data libraries, unless the default engine has been changed with the SAS system option ENGINE=. This engine is also the only engine under OS/390 that provides full support for catalogs in SAS Version 8; members of type ACCESS, PROGRAM, and VIEW; and SAS data libraries under UNIX System Services. It also supports multivolume SAS data libraries on disk. For further information on multivolume libraries, see Allocating Multivolume SAS Data Libraries.

Here are some other important characteristics of the V8 engine for direct access bound data libraries:

Here are additional characteristics of the V8 engine that apply to all library implementations (direct access bound library, HFS library, and hiperspace library):

How to Select the V8 Engine

There are four ways to select the V8 engine:

DCB Attributes for Direct Access Bound Libraries with the V8 Engine

The physical file label contains DCB information that describes the data set'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.

The following sections provide additional information about DCB parameters for the V8 engine. Also see DCB Attribute Options for more information.

External Allocation: V8 Engine

If you use a JCL DD statement or a TSO ALLOCATE command to allocate a new V8 SAS data library, and if you choose to specify DCB attributes, then you must specify the following DCB attributes:

If you do not specify DCB attributes for a new V8 SAS data library, then SAS supplies the above DCB attributes whenever the V8 engine has been either explicitly or implicitly assigned. (See How to Select the V8 Engine and How SAS Assigns an Engine When No Engine Is Specified for details about how engines are assigned.)

When allocating a V8 data library, choose an appropriate block size. Here are some guidelines. (See also the performance information in Optimizing I/O.)

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 a block size of 6144 by default.

If you specify a block size that is not an integral multiple of 512, then the number is rounded down to an integral multiple of 512.

Internal Allocation: V8 Engine

If you use the LIBNAME statement or LIBNAME function to allocate a new V8 SAS data library, SAS supplies the following DCB attributes for you:

You can override the default value of the BLKSIZE= system option by using the BLKSIZE= option in the LIBNAME statement or LIBNAME function.

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 the V8 Engine

The engine/host options that you can supply in the LIBNAME statement, LIBNAME function, or SAS Explorer New Library Assignment dialog box correspond to the JCL or TSO parameters that you would specify if you allocated the SAS data library externally. For bound libraries using the V8 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:

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 V8 Engine shows information that is generated by the V8 engine.

PROC CONTENTS Output Generated by the V8 Engine
                               The SAS System                              1
                                  The CONTENTS Procedure

   Data Set Name: WORK.ORANGES                        Observations:         4
   Member Type:   DATA                                Variables:            5
   Engine:        V8                                  Indexes:              0
   Created:       14:27 Tuesday, March 5, 1999        Observation Length:   40
   Last Modified: 14:27 Tuesday, March 5, 1999        Deleted Observations: 0
   Protection:                                        Compressed:           NO
   Data Set Type:                                     Sorted:               NO

                  -----Engine/Host Dependent Information-----

       Data Set Page Size:         6144
       Number of Data Set Pages:   1
       First Data Page:            1
       Max Obs per Page:           152
       Obs in First Data Page:     4
       Number of Data Set Repairs: 0
       Physical Name:              SYS96065.T142625.RA000.USERID.R0000180
       Release Created:            7.0000B2
       Release Last Modified:      7.0000B2
       Created by:                 USERID
       Last Modified by:           USERID
       Subextents:                 1
       Total Blocks Used:          1

           -----Alphabetic List of Variables and Attributes-----

#    Variable    Type    Len    Pos   Format      Informat   Label
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

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Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.