  Utilizing a full microscopic Bogoliubov-de Gennes (BdG) approach, we study
the equilibrium charge and spin currents in ballistic $SFSFS$ Josephson
systems, where $F$ is a uniformly magnetized ferromagnet and $S$ is a
conventional $s$-wave superconductor. From the spatially varying spin currents,
we also calculate the associated equilibrium spin transfer torques. Through
variations in the relative phase differences between the three $S$ regions, and
magnetization orientations of the ferromagnets, our study demonstrates
tunability and controllability of the spin and charge supercurrents. The spin
transfer torques are shown to reveal details of the proximity effects that play
a crucial role in these types of hybrid systems. The proposed $SFSFS$
nanostructure is discussed within the context of a superconducting magnetic
torque transistor.
