SAS(R) 9.1.3 Companion for z/OS

RELEASE Procedure
Releases unused space at the end of a disk data set
z/OS specifics: all
Syntax
PROC RELEASE DDNAME=file-specification ;
Details
Procedures under z/OS RELEASE Procedure 333
PROC RELEASE can be used with most sequential or partitioned data sets, not just
with a SAS data library that contains SAS data sets. However, PROC RELEASE is not
supported for, and cannot be used to release unused space from, the following types of
data sets:
3 the SAS WORK data library
3 extended partitioned data sets (PDSEs)
3 ISAM or VSAM data sets
3 multivolume SAS data libraries
3 external multivolume data sets.
If you delete some members from a SAS data library (using the DATASETS
procedure, for example), you can use the RELEASE procedure to release the unused
space at the end of the last member. You cannot use PROC RELEASE to release
embedded space. That is, you can release only space that follows the “Highest Used
Block,” as indicated by the CONTENTS or DATASETS procedure.
In order to use PROC RELEASE on a SAS data library, the data library must be
closed. If the library is open, SAS generates an error message. If you have assigned a
libref to the data library and have used some members of that library in your SAS
session, the library will be open. To close it, issue a LIBNAME statement of the
following form for each libref currently assigned to the library:
LIBNAME libref CLEAR;
Then issue a new LIBNAME statement for the data library and immediately run
PROC RELEASE. As an alternative to issuing a second LIBNAME statement, you can
simply specify the data library’s name (enclosed in quotation marks) as the value of the
DDNAME= option in the PROC RELEASE statement.
In the control language, you can release unused space by using specifications such as
SPACE=(,,RLSE) in the DD statement (in batch mode), or you can use the RELEASE
operand of the TSO ALLOCATE command. However, releasing unused space with
PROC RELEASE offers several advantages over methods provided by the operating
environment. For example, with PROC RELEASE, the user, not the operating
environment, controls when unused space is released. This advantage is especially
applicable to TSO users.
Another advantage of PROC RELEASE is that you can use PROC RELEASE options
to specify exactly how many tracks you want to keep or release. There is no danger of
erasing all or part of a data set because PROC RELEASE frees only unused space.
PROC RELEASE returns unused space to the pool of available space on the disk
volume. Once released, the space is still available for allocation to the data set,