VMS Help INITIALIZE, Qualifiers, /DIRECTORIES  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /DIRECTORIES=number-of-entries

    The effect of this qualifier depends on the disk structure:

    o  For ODS-1, /DIRECTORIES allows space for the specified number
       of directory entries to be reserved in 000000.DIR (the MFD).

    o  For ODS-2 and ODS-5, /DIRECTORIES allows the initial size of
       the MFD to be set. The specified number is divided by 16, to
       produce the number of blocks to preallocate. This number is
       then rounded up to a whole number of clusters.

    The number-of-entries value must be an integer between 16 and
    16000. The default value is 16.