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.