Does a call to a language handler provide a context/session, and somewhere to keep session data?

Given that a language handler would be expected to be persistent, and to support concurrent (and reentrant) calls
withina single database, is there a unique context or session identifier available? 

Is there a place to store data, to be retrieved later in the same session?

Is there a place to store data (a cache?) that has been retrieved from the database for use by concurrent sessions
usingthat database? 

Regards
David M Bennett FACS

Andl - A New Database Language - andl.org