The SORT verb dynamically allocates memory, which it releases when it finishes. Prior to doing this, however, it allocates a reserve area to be used by the SORT process should either the Input or Output Procedure need to use additional memory (for example, if they call another program). The value of the SORT_RESERVE variable determines the size of this area. It is expressed in kilobytes and can vary from 1 to 64. The default value is "16".