The SET LINES (abbreviated SE L) command controls the number of screen
 lines used in either of the screen versions of change mode.  Use this
 option to reduce the time it takes to refresh the screen image when
 editing on slow terminals.

 Format: SET LINES n

 where n is the number of lines to use.  n must be between 1 and 22.  By
 default, n is set to 22 lines.  If the cursor limits are larger than n-1
 they are reduced to n-1.  See SET CURSOR.