The BLKALLOC option
causes LIBNAME statement processing to use a nonzero block size value
when allocating a direct access or sequential access bound library.
The block size value is derived from one of the following sources,
which are listed in order of precedence:
-
the value specified
with the BLKSIZE host option of the LIBNAME statement
-
the value specified
with the BLKSIZE system option
-
the value specified
with the BLKSIZE(OTHER) system option
-
The block size value
is set only if both of following conditions are met:
-
The library is not already allocated
either externally or internally to SAS.
-
The purpose of BLKALLOC
is to ensure that the library data set is allocated with a default
nonzero block size value, even if the library is not accessed by SAS
in the current session, and therefore not initialized. The block
size value thus set is saved in the data set label (format-1 DSCB
in VTOC). If such a library is accessed in a later SAS session, it
is treated as a preallocated, but uninitialized, library.
Note: The BLKALLOC option has no
effect for libraries that were already allocated, either externally
or internally to SAS.