Library /sys$common/syshlp/dbg$help.hlb DEBUG, Messages, HEIGHTDIFF  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 desired height of specified_height is not allowed, height is set to
 actual_height

    Facility: DEBUG, VMS Debugger

    Explanation: The device specified by DBG$OUTPUT had a screen
    height that wasn't in the range of 18-100.

    User Action: Use SHOW TERMINAL command and verify that the
    terminal height is correct, it is in the range 18-100, and is
    pointing to a valid terminal type.