In short, you don't.
However, through the use of SRM, there is a thing called bannanas that can prolly help you with what you need. Banannas are supposed to be persistent variables.
Anyways, do a search on google for php and srm.
Another option considering that srm is still in development is shared memory. I've used for a couple of things. It's pretty cool stuff.
Hope that helps.
Cheers,
BDKR