12.1.2 Scrollback

Command: defscrollback num

(none)
Same as the scrollback command except that the default setting for new windows is changed. Defaults to 100.

Command: scrollback num

(none)
Set the size of the scrollback buffer for the current window to num lines. The default scrollback is 100 lines. Use C-a i to view the current setting.

Command: compacthist [state]

(none)
This tells screen weather to suppress trailing blank lines when scrolling up text into the history buffer. Turn compacting `on' to hold more useful lines in your scrollback buffer.