(Alpha and Integrity servers) If a file is connected to RMS with
    the RMS global buffer DEFAULT option enabled, either a percentage
    (GB_DEFPERCENT) of the file is cached or up to GB_CACHEALLMAX
    blocks of it are cached, whichever results in a larger global
    buffer count. A percentage greater than 100 percent can be
    specified for GB_DEFPERCENT to provide growing room for a file
    in the global cache.

    Note that although a maximum cache size of %x7FFFFFFF is
    supported for an indexed file, sequential and relative file
    organizations are restricted to a maximum cache size of 32767.

    GB_DEFPERCENT is a DYNAMIC parameter.