I've been seeing a lot of questions on the Data Studio forum around using the Data Studio free query tuning capabilities. In case this audience is also interested, a couple of technotes have been recently released that will hopefully clear things up.
One issue has to do with the server side configuration you need to have on the server to use query tuning.
Find out more in this technote:
Configuring DB2 for z/OS Subsystems for Tuning Queries with IBM Data Studio (stand-alone package)
And this technote gives you step by step instructions on migrating projects from Optimization Service Center to Data Studio (stand-alone version
Hope this helps!