What format and version?
Separate how? Existing outside the story's normal scope? Just simply not accessible to the player?
What do you mean by store? Store how? A list of variables set to specific values? User / play defined values? Static values? A list of initialized values? Just a list of variables names?
Use later for what? To reset variables? To initialize them? To set them to specific values based on the passage? Just to display?
The simple answer to your question is probably yes. But depending on your goals and your format, the actual answer will change pretty dramatically.