MCAS is flaps up only. Furthermore, it is not needed to provide anticipatory stabilizer trim in order to maintain sufficient pitch control power via the column/elevator. If column/elevator were not able to generate enough pitch control power without moving the stabilizer other than to provide long term pitch trim that would constitute a certification issue that could not be addressed via either stabilizer trim or a stick pusher.
The certification issue that is addressed by MCAS is that the inherent pitch up encountered at high AOA, aft CG, flaps up is such that increased AOA can require relaxing of the column pull needed to initiate the maneuver. Requirements call for stick force needed to increase AOA up to stick shaker must not drop with increasing AOA.