VMS Help Sys Parameters, VCC_MAXSIZE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (Alpha only) The static system parameter VCC_MAXSIZE controls the
    size of the virtual I/O cache. VCC_MAXSIZE, which specifies the
    size in blocks, is 6,400 by default.

    The virtual I/O cache cannot shrink or grow. Its size is fixed at
    system startup.

    This special parameter is used by Compaq and is subject to
    change. Do not change this parameter unless Compaq recommends
    that you do so.

    VCC_MAXSIZE is an AUTOGEN parameter.