It depends on the plane and on the size/shape of those three items.

Some TATL planes (like the 763s) have center bins which can't hold full-size carryons, and you can bring endless small carryons of the right (or malleable) shape and have plenty of room there to stow them, but just one full-size carryon and just one oddly shaped personal item you might have problems with because both might need to go in the bigger bins above the windows, which there's much more competition for.