Hi Jun,
The Zigbee stacks function with many tasks that has certain functionality each one. Receive, send, attend events are an example of the functionality each one has. If you want to share information between these tasks, you'll need to create a Queue, and with the function ZQ_bZQueueReceive and ZQ_bZQueueSend, pass the information between them.
However if you're working with our Zigbee Stack, this message management is handled in the stack, and you'll only need to call the APIs like ZPS_eAplZdoPoll, ZPS_eAplZdpActiveEpRequest, etc. (Please check the ZigBee 3.0 Stack User Guide to know the functionality of these functions) to manage the transmission and reception.
Here's the link to the Zigbee User Guide.
https://www.nxp.com/docs/en/user-guide/JN-UG-3113.pdf
I hope this helps you.
Best Regards,
Alexis Andalon
