  We develop a procedure for calculating the magnetic properties of a
ferromagnetic Heisenberg film with single-ion anisotropy which is valid for
arbitrary spin and film thickness. Applied to sc(100) and fcc(100) films with
spin S=7/2 the theory yields the layer dependent magnetizations and Curie
temperatures of films of various thicknesses making it possible to investigate
magnetic properties of films at the interesting 2D-3D transition.
