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

    (Alpha only) The dynamic system parameter VCC_MAX_IO_SIZE
    controls the maximum size of I/O that can be cached by the
    Extended File Cache. It specifies the size in blocks. By default,
    the size is 127 blocks.

    Changing the value of VCC_MAX_IO_SIZE affects reads and writes to
    volumes currently mounted on the local node, as well as reads and
    writes to volumes mounted in the future.

    If VCC_MAX_IO_SIZE is 0, the Extended File Cache on the local
    node cannot cache any reads or writes. However, the system is
    not prevented from reserving memory for the Extended File Cache
    during startup if a VCC$MIN_CACHE_SIZE entry is in the reserved
    memory registry.

    VCC_MAX_IO_SIZE is a DYNAMIC parameter.