Optimizing Performance

Loading SAS Modules Efficiently

SAS software has three possible program configurations:

unbundled
bundled (LPA/ELPA version)
bundled (non-LPA version).

In an unbundled configuration, all modules are loaded individually from the SAS software load library. Running in this manner is not generally recommended because it significantly increases library-directory searches and I/O. However, SAS is shipped with this setting by default because some of the installation tasks must invoke SAS before the installer has had the opportunity to select a bundled version.

In the two bundled configurations of SAS, many individual modules are combined into one large executable file. Invoking a bundled version of SAS eliminates both wasted space between modules and the overhead of loading each module individually. Performance is also improved slightly.

In a multiuser SAS environment, the most effective way to reduce memory requirements is to use the LPA/ELPA bundled configuration. This configuration dramatically reduces each user's working-set size.(footnote 1)

The non-LPA bundled configuration is intended for sites that do not want to place SAS modules in the Link Pack Area. In this configuration, the bundle is loaded into each user's address space. Although this decreases library-directory searches and I/O, it has the unfortunate side-effect of increasing individual working-set sizes. Therefore, this method is not recommended if you have many SAS users at your site.

For detailed information about the bundled configurations and how to install them, see the installation instructions for SAS software in the z/OS environment.

FOOTNOTE 1: Working-set size is the amount of real system memory that is required to contain a) the programs that consume most of the system execution time, and b) the data areas that these programs reference.

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