Are you sure the SSAS needs the memory?

SSAS does not grab and hold memory like SQL Server, it only takes the memory that is necessary to keep the model in memory.

The LowMemoryLimit is not the minimum amount of memory taken ( 512 * 65% ~ 330), but the Specifies the threshold amount of memory allocated by Analysis Services at which it will begin cleaning caches to lower memory usage.

You can find more details here: http://msdn.microsoft.com/en-us/library/dn393915.aspx