The other people's answer are correct. I will add that 12 GiB is not a lot of memory, so 5.3 GiB for services is within the limits
HOWEVER
I have been myself experiencing random high RAM consumption by services (20/28GiB), which I could not explain as it doesn't show up in top/htop or whatever. Even shutting down all jails, VMs and services, it doesn't go away except misteriously for no reason after a day or so.
In my case the problem seems to be rrdcached.
As soon as I restart that service (service rrdcached onerestart), services go down to normal usage, which in my case sits between 7 and 10 GiB because of a number of jails).