Why my resources is not been release when my machines is down?

[Kalil de Albuquerque Carvalho]

Hello all.

I'm testing Cloudstack 4.15 and it is strange, or, probably, I'm doing 
same mistakes,  that when I halted my VM's the resources are not been 
released for the system. It is like when the VM is created the resource 
it is reserved exclusively for it.

Some one can tell me where I can find the documentation that I can get 
this information and how to work with it?

Any one can help me to understand what it is happening?

Best regards.