Where does systemd-logind.service store its stats (e.g. loginctl things)?

This is more out of interest than necessity but I'd like to know where
systemd-logind.service stores its persistent data. E.g. in particular
when I run 'loginctl enaable-linger chris' where is the required flag
set?

It must be a persistent location as 'enable-linger' obviously survives
a reboot, but I just can't find where it is.

There is a sort of reason for wanting to know this, I want to backup
the information so that if/when I rebuild a system it doesn't get
lost. At present I just have a note to myself in my configuration
repository that 'loginctl enable-linger chris' needs to be run on a
couple of systems but it would be nicer if I could automate it.