/RESERVE=n
       /NORESERVE (default)

    Allows you to reserve space at the top of the first page of the
    index for text or white space that you want to include with the
    /REQUIRE=filespec qualifier. Determine how many lines of text or
    white space you are adding to the top of the first page of the
    index. Use this number as the value n for the /RESERVE qualifier.