R/3 session with VC

Hi,

I have an R/3 system connected to the portal. I use this R/3 system in my Visual Composer application. There are many RFC calls made to the R/3 system. The first RFC call saves certain global data in the function group and the subsequent calls use that global data. But the function group is re-loaded each time. User session is not maintained.

How do I keep the user-session in R/3 until the user logs off from the portal. Is there any setting to control this or its the only behaviour.

Thanks.

Srinivas.