Change session save place

Right now every session saves in /tmp

But what if i want it to automatic save for every website in their own map
like when you create a new domain, theres a tmp folder in the public_html
I want it to save their for every single domain i got, not in the same /tmp folder

And is there a session limiter or something, because one of my websites has stopped creating new session files, only the one which already is saved can log in on my page

If your using php-fpm

In each users pool file.
php_value[session.save_path]    = path/to/savepath. Ex: /home/user/tmp
 
In PHP.ini session.save_path a default location can be set server wide.