Config requirements for connecting Powerconnect switches together for optimal bandwidth

I have three Powerconnect switches in hub/spoke configuration.  A 5324 that serves as the hub (with gateway, servers, and mpls plugged into it) and two 5448s that serve as the spokes of my network (workstations).  Currently, the links between switches are LAGS that utilize two ports each.  Aside from the LAGs i have made no changes to the port settings on any switch. Are there any additional settings that i need to configure to let the switches know that the LAGS are switch to switch connections and not just standard ports?  Is there any other optimization that i can do to make sure these switches are working efficiently?  (I already have Qos setup for critical data).