DFSORT's use of virtual storage from the primary address space is limited by several factors, most notably system (for example, REGION, IEFUSI) and DFSORT (for example, TMAXLIM, SIZE) parameters, defaults, and exits. While DFSORT can never exceed the system limits, those limits usually exceed the virtual storage DFSORT needs for most applications. As a result, the DFSORT limits usually control the amount of virtual storage used by DFSORT.

Dynamic Storage Adjustment permits a range to be specified for the default amount of virtual storage for sorts, provided SIZE/MAINSIZE=MAX is in effect. This range starts with the value specified for TMAXLIM and goes up to the value specified for DSA. For most sorts, DFSORT limits its use of virtual storage to TMAXLIM. However, for larger sorts, DFSORT automatically optimizes performance by increasing the amount of virtual storage it uses, up to but not exceeding the DSA value.

See Installation considerations and Run-time considerations for further details on the best way to tune DFSORT's use of DSA.