That will depend on the size of the aircraft. Depending on the specific aircraft, it may have little to know overhead space or it may have standard sized OH's. Take a look at your e-ticket receipt. It should show the aircraft.

Note that if you do have to check your larger carry-on at the gate, it will be returned to you planeside (or in the jetway) on arrival. Nonetheless, make certain that valuables and medications go in the small carryon.