We analyze a mean field model for 3d anisotropic superconductors with a layered structure, in the presence of a strong magnetic field. The mean field model arises as the Gammalimit of the Lawrence-Doniach energy in certain regimes. A reformulation of the problem based on convex duality allows us to characterize the first critical field H c 1 of the layered superconductor, up to leading order. In previous work, Alama-Bronsard-Sandier [2] have derived the asymptotic value of H c 1 for configurations satisfying periodic boundary conditions; in that setting describing minimizers of the Lawrence-Doniach energy reduces to a 2d problem. In this work, we treat the physical case without any periodicity assumptions, and are thus led to studying a delicate and essentially 3d non-local obstacle problem first derived by Baldo-Jerrard-Orlandi-Soner [6] for the isotropic Ginzburg-Landau energy. We obtain a characterization of H c 1 using the special anisotropic structure of the mean field model.