The USEDIRECTIO= data
set option turns on direct file I/O for a data set that is listed
on a DATA statement. The associated libref must have been defined
with the ENABLEDIRECTIO option in the LIBNAME statement.
Using ENABLEDIRECTIO
on a LIBNAME statement makes direct file I/O possible for data sets
in that library. Direct I/O itself is not turned on. You must use
the USEDIRECTIO= option to produce direct file I/O.
You can turn on direct
file I/O in two ways:
-
Use both the ENABLEDIRECTIO and
USEDIRECTIO= options in the LIBNAME statement:
libname libref-name '.' ENABLEDIRECTIO USEDIRECTIO=yes;
In this case, SAS uses
direct file I/O on all SAS I/O data sets that are opened using the
libref
libref-name.
-
Use ENABLEDIRECTIO in the LIBNAME
statement and use USEDIRECTIO= in a DATA statement:
libname libref-name '.' ENABLEDIRECTIO;
data libref-name.data-set-name (USEDIRECTIO=yes);
In this case,
libref-name.
data-set-name will be opened for direct file I/O. Other SAS I/O data sets referenced
by
libref-name will not use
direct file I/O.
USEDIRECTIO= by itself
has no effect. Neither of the following statements open a data set
for direct file I/O:
libname libref-name '.' USEDIRECTIO=yes;
data libref-name.data-set-name (USEDIRECTIO=yes);