I am not aware of any document explaining the ATM debug output. However it seems your errors are caused because your VC input queue is full and that is why you are receiving ATM0: AAL5 rx errors and the message QUEUE_PER_VC enqueue fails!
I would try increasing the hold-queue value in your PVC configuration and check if the messages dissappear.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...