The minimum number of lines in the Source window or in the Command window one, not counting the Source window line that displays the current module name. On a standard 24-line terminal, the maximum number of lines in either window is 18, or L-6 where L is the number of lines that the terminal supports.
The argument of a GROW command is not the new window size but the increment to the current window size. To change the size of a window in the Debugger screen, enter a GROW command to produce window sizes within this range.