In this paper, we present a novel and systematic approach for the design of shared memory architectures in the case of application-specific multiprocessor system-on-chip. This paper focuses on a memory allocation step which is based on an integer linear programming model. It permits to obtain an optimal distributed shared memory architecture minimizing the global cost to access the shared data in the application, and the memory cost. Our approach allows automatic generation of an architecture-level specification of the application. The effectiveness of this approach is illustrated by a packet routing switch example.