[libvirt-users] limit memory and CPU when using libvirt-sandbox

I'm considering using virt-sandbox with lxc to sandbox and execute untrusted code like python scripts and compiled C code. Is it possible to limit CPU and Memory like is possible with lxc-execute and a config file? What are the defaults security settings? Is it completely isolated by default? What's the difference between lxc-execute and libvirt-sandbox? How can I use it in ubuntu? Thanks