| SAS Companion for the OS/390 Environment |
In some cases, you may choose not to specify an engine name
in the LIBNAME statement or LIBNAME function, or you may choose not to issue
a LIBNAME statement or function for a data library that was allocated externally.
For these situations, you need to know how SAS assigns an engine to the library.
- For a new SAS data library on disk, SAS uses the
value of the ENGINE= system option as the engine. (Exception: For a new sequential-format
data library on disk, you must include the engine name in the LIBNAME statement
or LIBNAME function.)
- For an existing SAS data library on disk, SAS
examines the library's DCB attributes to determine which engine to use.
- If DSORG=PS and RECFM=FS, SAS opens the library
and inspects the header information to determine if it should use the V8 engine
or V6 engine. Because this operation can degrade performance, it is more efficient,
if possible, to specify the engine in the LIBNAME statement or LIBNAME function.
- If DSORG=DA, SAS uses the V5 engine. The V5 engine
is supported for read access only.
- If DSORG=PS and RECFM=U, SAS uses the current
value of the SEQENGINE= system option.
- If either DSORG= or RECFM= is undefined, SAS uses
the current value of the ENGINE= system option.
- For new tape data sets, SAS uses the current value
of the SEQENGINE= system option.
- For existing tape data sets, instead of looking
at the characteristics of the tape, SAS opens the file and reads the first
record to determine whether it should use V8TAPE, V7TAPE, V6TAPE, or V5TAPE.
The V5TAPE engine is supported for read access only.
- For an existing directory in UNIX System Services,
SAS uses the V8 engine automatically.
Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
