Library /sys$common/syshlp/pca$help.hlb SET, DISPLAY, Qualifiers, /SIZE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SIZE:n

    Sets the maximum size of a normal output display to be n lines.
    If more than n lines are written to the display, the oldest lines
    are lost as the new lines are added. If you omit this qualifier,
    the maximum size is set to 50 lines.

    For plot displays, n specifies the number of lines of PLOT or
    TABULATE output to be buffered internally by the Analyzer at one
    time. There is usually no need to change this number.