heap configuration when applying MessageQ in Syslink

I am developing my OMAPL138 board, and I plan to use MessageQ in Syslink_2_21_01_05 for communication for ARM and DSP.

In the example of MessageQ provided by TI, four parameters for the heaps applied by message  are set, which include heapParams.blockSize and heapParams.numBlocks . The configuration is as follow:

heapParams.blockSize = 64; 
heapParams.numBlocks = 10;

I just wonder based on what, these two are decided. In the API reference,  a unit called MAU is mentioned. And I don't what it is. 

I think it might be easy question for others, so any idea please?