SAS Companion for the OS/390 Environment

Efficient Sorting

Consider changing the values of SORTPGM= and SORTCUTP=

The SAS System includes an internal sort program that is often more efficient than host sort programs for sorting small volumes of data. Host sort programs are generally more efficient when the data volume is too high to perform the sort entirely in memory.

Under OS/390, the default value of the SAS system option SORTPGM= is BEST. This value causes SAS to use the SAS sort program for less than 4M of data; for more than 4M of data, SAS uses the host sort program. You use the SORTNAME= system option to specify the name of the host sort program.

The 4M limit is the default value that is specified by the SORTCUTP= system option, which is specific to OS/390. You may want to change the value of this option in order to optimize sorting for your particular applications.

Take advantage of the DFSORT performance booster

If your installation uses Release 13 or later of IBM's DFSORT as its host sort utility for large sorts, then you can take advantage of a DFSORT "performance booster." To do so, specify SORTBLKMODE in an OPTIONS statement, in the OPTIONS parameter list of the SAS cataloged procedure, or in a configuration file.

SORTBLKMODE causes SAS to work in conjunction with DFSORT to process your SAS sorting applications faster. SAS applications that use either PROC SORT or PROC SQL for sorting can take advantage of this "performance booster." For large sorts of approximately 100,000 observations or more, CPU usage may be reduced by up to 25%.

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