There are a couple of ways you can get a "status bar" that I can think of:
One status bar is the
caption. It normally only appears with multiple windows (split screen), this setting is
caption splitonly. The always-there version is
caption always. It doesn't seem to have a way to tie it to the number of screens ("tabs") open. If it goes away by hitting your command character (^a) and typing
:caption splitonly then that was what you're looking at, and putting
caption splitonly in your .screenrc will get rid of it.
The other status bar is the
hardstatus which refers to the terminal's "hardware status" line. This one usually gets displayed in the title bar of your window, but it could be forced to the bottom of the terminal with the setting
hardstatus alwayslastline. Setting
hardstatus off turns it off. This is always either "on" or "off".