/sys$common/syshlp/helplib.hlb Sys Parameters, WSINC  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Decreasing the value of this parameter tends to reduce the speed
    with which working set limits are increased when the need arises.
    Normally, you should keep this parameter at a high value because
    a rapid increase in limit is often critical to performance.

    On VAX systems, WSINC specifies the number of pages by which
    the limit of a working set is automatically increased at each
    adjustment interval (which is quantum end). At a setting of 150,
    for example, the system increases the limit of a working set by
    150 pages each time an increase is required. On VAX systems, the
    default value is 150 512-byte pages.

    On Alpha systems, WSINC specifies the number of pagelets by which
    the limit of a working set is automatically increased at each
    adjustment interval (which is quantum end). At a setting of
    150, for example, the system increases the limit of a working
    set by 150 pagelets each time an increase is required. On
    Alpha systems, the default value is 2400 512-byte pagelets
    (150 8192-byte Alpha pages).

    A value of 0 for WSINC disables the automatic adjustment of
    working set limits for all processes. Limits stay at their base
    values. You can disable the automatic adjustment of working
    set limits on a per-process basis by using the DCL command SET
    WORKING_SET.

    WSINC has the DYNAMIC and MAJOR attributes. On Alpha systems,
    WSINC also has the AUTOGEN attribute.