Application layer multicast (ALM) algorithms are either similar or conceptually based on network layer multicast's cost functions. In this research work, a new application-network cross layer multi-variable cost function is proposed. It optimizes the variable requirements and available resources from both the application and the network layers. It can dynamically update the available resources required for reaching a particular node on the ALM's media distribution tree. Mathematical derivation and theoretical analysis have been provided for the newly proposed cost function so that it can be applied in more general cases of different contexts. An evaluation platform of an overlay network built over a convergent underlay network comprised of a simulated Internet topology and a real 4G mobile WiMAX IEEE802.16e wireless network is constructed. The performance of the newly proposed cross-layer multi-variable cost function is evaluated and compared with conventional cost functions in scalable video coding-based services such as video multicast and video conferencing services using the evaluation platform. Intensive evaluation results have shown that the newly proposed cross-layer multi-variable cost function outperforms the conventional cost function and improves the performance of multimedia services on dynamic convergent network environments