The present work fits within the general study of communication and control co-design, where the mean square stabilization of continuous-time networked control systems over stochastic multiplicative input channels is addressed. Motivated by the limited communication capacity and network resource allocation in multiple channel communication systems, we assume that the overall quality of service defined in this paper is fixed and can be assigned among the input channels. We show that there exists a minimal requirement on the overall quality of service for achieving the mean square stabilization of the networked system. For the case of static state feedback, a tight lower bound on the overall quality of service for mean square stabilization is derived in terms of the instability degree of the plant. In the case of output feedback, additional limitations are induced by nonminimum phase zeros, where both stabilization over a single-input channel and stabilization of essentially triangular plants over multi-input channels are studied. The application of the results to vehicle platooning is demonstrated.