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SAS Companion for the OpenVMS Environment

How SAS Assigns an Engine When No Engine Is Specified

It is always more efficient to explicitly specify the engine name than to ask the SAS System to determine which engine to use. To assign an engine name, use a LIBNAME statement or LIBNAME function, or the LIBASSIGN command in the command window. If you use the LIBASSIGN command the Default engine-that is, BASE-is listed in the Engine: field of the New Library dialog box; when you select [OK], you automatically select this default engine.

If you do not assign an engine name, SAS looks at the OpenVMS file types of the files that exist in the specified directory and uses the following rules to determine which engine to assign:

If the directory contains SAS data sets from only one of the native library engines that are supported, then that engine is assigned to the libref.
If the directory contains no SAS data sets, then the default engine is assigned to the libref. The default engine is determined as follows:
- For SAS data libraries on disk, the default engine is determined by the value of the ENGINE= system option. By default, the ENGINE= system option is set to V7. However, you can change the value of this system option if you prefer to use a different engine as the default engine for disk libraries. Other valid values are V6 and CONCUR. For more information about the ENGINE= system option, see ENGINE= and SAS Language Reference: Dictionary.
- For sequential-format SAS data libraries (either on tape or disk), the default engine is determined by the value of the SEQENGINE= system option. By default, SEQENGINE= is set to TAPE. The other valid values are V7TAPE and V6TAPE.
A directory that contains SAS data sets from more than one engine is called a mixed-mode library. The SAS System assigns the default engine to mixed-mode libraries.

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