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

 screen too big for Screen Mode width must be less than maximum_
 width, height less than maximum_height

    Facility: DEBUG, VMS Debugger

    Explanation: The current screen dimensions are too large for
    debugger screen mode.

    User Action: Change the screen dimensions to be small enough for
    debugger screen mode.