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

       /VERSION_LIMIT[=n]

    Specifies the total number of versions that a file in the
    specified directory can have. If you do not specify a version
    limit, a value of 0 is used, indicating that the number of
    versions of a file is limited only to the Files-11 architectural
    limit-32,767. If you change the version limit for the directory,
    the new value applies only to files created after the change has
    been made.

    The SET DIRECTORY version limit value refers to the number of
    files with the same file name and type that can exist in the
    directory at one time. It has no effect on the version number
    field of a particular file specification. Use the SET FILE
    command to set limits on file version numbers.

    To find out the current version limit for a directory, use the
    DIRECTORY/FULL command on a directory file and look at the File
    Attributes component of the output.