mbed-os/components/TARGET_PSA/spm/mbed_lib.json

{
    "name": "spm",
    "config": {
        "ipc_max_num_of_channels": {
            "help": "maximum number of PSA channels that can be opened at the same time",
            "value": 10
        },
        "ipc_max_num_of_messages": {
            "help": "maximum number of messages SPM Core can handle at a time",
            "value": 10
        }
    }
}