SAS(R) 9.1.3 Companion for z/OS

Using SAS Data Libraries Assigning SAS Data Libraries Externally 57
A partially qualified directory path may also be specified, in which the path specified
is relative to the current working directory. For example, if the current working
directory is /u/user905, the example below would be equivalent to the example above:
data ’MyProject/Member1’; x=51; run;
proc print data=’MyProject/Member1’; run;
It is not necessary to specify the SAS file extension to a member if the member type
is implied by the context, and if the default engine is the desired engine. However, if
you wanted to access TAPE engine files that exist in the same directory as BASE
engine files, you would need to specify the extension as shown below:
proc print data=’NewProject/member1.sas7sdat’; run;
Assigning SAS Data Libraries Externally
SAS data libraries can be assigned externally by first allocating a DDname to the
library via JCL or a TSO command. Assignment of the library is then completed by
specifying the DDname as a libref within SAS. At that point, SAS selects an engine for
the library according to the rules detailed in the section “How SAS Assigns an Engine”
on page 59. However, if the reference to the libref is in a LIBNAME statement that
explicitly specifies which engine should be used, SAS uses the rules described in
“Specifying an Engine for Externally Allocated SAS Data Libraries” on page 59.
Despite the advantages of assigning SAS data libraries internally, assigning SAS
libraries externally also has advantages, which might be important in some cases.
3 You might not want to allow a SAS job running in batch to start until the data
libraries it needs to access are available. If you allocate the data libraries using
DD statements in JCL, the z/OS job scheduler will automatically ensure that the
data libraries are accessible:
3 by granting the job exclusive access to the data library if DISP=OLD is
specified
3 by granting the job shared access to the data library if DISP=SHR is specified.
3 The syntax of the JCL DD statement and the TSO ALLOCATE command is more
comprehensive than that of the LIBNAME statement. For example, in order to
specify a list of more than 30 volumes, it is necessary to use external allocation.
3 If a particular SAS program uses an externally assigned SAS data library, it is
possible to change the library that the program acts upon merely by changing the
JCL or TSO clist that invokes SAS, as opposed to changing the program. This may
prove to be convenient in some circumstances.
Note:
3 Because direct bound data libraries are not partitioned data sets (PDS or PDSE),
they cannot be concatenated via external allocation. An attempt to concatenate
library data sets in this way is ignored with a warning, and only the first library
in the concatenation is recognized. However, sequential access bound libraries can
be concatenated if they are allocated with DISP=SHR.
3 SAS will not attempt to de-allocate a library data set that was allocated external
to SAS. Therefore, externally assigned bound libraries will remain allocated until
the end of the job step or until a TSO FREE command is issued. However, if
FREE=CLOSE is specified on the external allocation for a direct access bound
library, the library will be de-allocated by the system when the last libref assigned
to the library is cleared. This exception does not apply to sequential access bound
libraries; they would not be freed at de-assign time even if FREE=CLOSE was
specified.