Latitude E5430 shared video memory size

Hello, 

I have a Latitude E5430 with an integrated Intel HD4000 graphics adapter. I know this model uses the system RAM, and in the current configuration it only uses 256MB. I have 4GB of RAM, and would like to allocate more of that for the graphics card usage.

However, in the BIOS I only see an option to see what the current configuration is, not change it.

Is there a way to change this size? If so - how is it done? am I missing something in the BIOS?

Thanks.