SAS(R) 9.1.3 Companion for z/OS

46 HFS Libraries Chapter 2
3 To release the library data set prior to the end of the SAS session, specify the SAS
TAPECLOSE=FREE system option prior to the SAS DATA step or procedure that
will write the members of the library. For tape libraries, this step is necessary to
make the tape device and volumes available for other jobs prior to the end of the
SAS session.
Controlling Library Block Size
Because sequential access bound libraries use RECFM=U, the block size value is an
upper limit for the maximum size of a block. The value that SAS uses for any given
session, for either a new or existing library, is specified by the user from the following
hierarchy of sources:
3 the block size value specified on allocation, either in the LIBNAME statement or,
for external allocation, in the DD statement or TSO ALLOCATE command
3 the block size value specified in the data set label, that is, the value specified on
the DISP=NEW allocation that created the data set
3 32760.
HFS Libraries
A hierarchical file system (HFS) library is a collection of SAS files of the same engine
type that are stored in a single directory of the HFS of z/OS UNIX System Services
(USS). Each SAS library member resides in a separate HFS file. USS is a default
component of z/OS, and the availability of HFS is limited only by the extent to which it
has been implemented at a particular installation.
Note: In addition to the original HFS implementation, z/OS also provides another
UNIX file system known as zFS. zFS, which provides certain performance and
manageability benefits, is functionally equivalent from the perspective of a SAS user.
All information regarding HFS libraries applies equally to SAS files that reside in a
zFS file system. Whether the HFS or zFS implementation is used for a particular file
system is controlled by your systems administrator, not by SAS. R
HFS libraries provide many important capabilities that are not available in other
types of library implementations:
3 Members of HFS libraries can be processed by versions of SAS running in other
operating environments via the SAS cross-environment data access (CEDA)
facility. The individual SAS files can be copied (via a utility such as FTP) to other
operating environments and can be directly read by the versions for the target
operating environment. Conversely, SAS files created in most other operating
environments can be copied to an HFS directory and read directly by the z/OS
version of SAS via CEDA. This technique can be further extended by using the
network file system (NFS) capability of z/OS to either mount directories that exist
on remote hosts (NFS client) or to share an HFS directory with other hosts (NFS
server).
3 HFS directory names can contain mixed case, and they can also be longer than a z/
OS data set name. The directory hierarchy provides more flexibility for organizing
files.
3 Multiple SAS jobs can simultaneously update different members of the same
library. This provides more flexibility than that of direct access and sequential
access bound libraries, which only permit one SAS job to have update access to a
library at a given time.
3 Allocating and assigning an HFS library is very straightforward. The LIBNAME
statement merely needs to specify the libref, the HFS directory path, and perhaps