Optimizing Performance

Some SAS System Options That Can Affect Performance

The MAUTOSOURCE and IMPLMAC SAS system options affect the operation of the SAS autocall macro facility, and they interact in a way that you should be aware of.

Specifying IMPLMAC enables you to use statement-style macros in your SAS programs. With IMPLMAC in effect, each SAS statement is potentially a macro, and the first word (token) in each statement must be checked to determine whether it is a macro call.

When IMPLMAC is in effect without MAUTOSOURCE, no special checking takes place until the first statement-style macro is compiled. When both IMPLMAC and MAUTOSOURCE are in effect, however, this checking is done unconditionally. The initial occurrence of a word as the first token of a SAS statement results in a search of the autocall library. There can be a significant number of directory searches, especially when a large DATA step is compiled, in addition to the CPU time that is consumed by maintaining and searching the symbol table.

The combination of MAUTOSOURCE and IMPLMAC can add 20% to CPU time and 5% to I/O for a non-trivial job. Therefore, for best performance, leave NOIMPLMAC as the installation default.

REXXMAC

When SAS encounters an apparent SAS statement that it does not recognize, it typically generates a "statement is not valid" error message in the SAS log. However, when the REXXMAC system option is in effect, SAS passes the first word in the apparent statement to the z/OS REXX processor, which looks for a member by that name in the SASREXX library. Hence, a mistyped statement could have unintended results and could have a negative impact on performance. For more information, see REXXMAC System Option: z/OS and REXXLOC= System Option: z/OS.

SPOOL/NOSPOOL

The SPOOL system option is appropriate when you are running SAS interactively, without using the windowing environment. When SPOOL is in effect, SAS input statements are stored in a WORK library utility file; they are retrieved later by %INCLUDE and %LIST commands. SAS is shipped with SPOOL as the default setting for interactive sessions, but you might want to consider resetting it to NOSPOOL for batch jobs. In a batch job that has a large number of input lines, NOSPOOL can reduce I/O by as much as 9%.

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