If a file is connected to RMS with the RMS global buffer DEFAULT
    option enabled, the number of blocks cached is either a maximum
    of the GB_CACHEALLMAX parameter or a percentage of the file,
    whichever results in a larger global count.

    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_CACHEALLMAX is a DYNAMIC parameter.