have you got electrical drawing for this particular mazak? At the very beginning there is M code list, ever since Matrix control they moved M codes list into machine manuals.
if you have manual , and it says you have this M360 ( strange but I saw it as OPTION) , in your manual.............and your machine has actually those pistons to clamp and stop SS. Than you have to check all electrical connection and just go into MDI , send it M319 , then M360, than find inside electrical drawing Y- output which is responsible to activate SS clamp pistons, then go to LADDER DIAGRAM ( PLC) and see if it is actually activated as sometimes it can be one of those stupid parameters not ON for you to be able to use this M code. Very easy to fix.