Critical current densities J(c) and normalized flux creep rate S(= dln M/dln t) have been measured as a function of the perpendicular field H(perpendicular-to) in low-T(c) Pb/Ge multilayers, which can be used to model the superconducting properties of the layered high-T(c) cuprates. By taking a proper Ge separator thickness a field-induced crossover between two different pinning regimes can be observed. This transition leads to an anomalous behavior of J(c)(H(perpendicular-to)) and S(H(perpendicular-to)) in Pb/Ge multilayers, while a single Pb film demonstrates a monotonic suppression of J(c) by H(perpendicular-to). These data have been analyzed in the framework of the collective pinning (CP) theory of magnetically coupled superconducting planes: the J(c)(H(perpendicular-to)) anomaly is interpreted as a crossover from three-dimensional (3D) flux lines in low fields to two-dimensional (2D) pancake vortices in higher fields. This interpretation has also been confirmed by the suppression of the J(c)(H(perpendicular)) anomaly in the Pb/Ge multilayers with a square lattice of holes, forming additional defects for the confinement of the flux lines and for the expansion of the 3D regime.