Abstract: A communication device and associated method which is configured to utilize an API constraint language for communication of resource constraints between different layers of a communication stack. A first layer of the communication stack executing in a first communication device may receive application programming interface (API) messages from a second layer of the communication stack also executing in the first communication device. In addition, the first layer may receive resource constraints with the one or more API messages. These one or more resource constraints may be generated by the second layer, or other software executing in the communication device. The first layer may then execute communication functions based on the API messages and subject to the resource constraints. The resource constraints may affect usage of hardware and/or software resources of the first communication device during execution of the communication functions.