How to stretch a table

I have a custom z table and attached it to parameter transaction (SM30 etc) for maintenance.

Now when I enter the T Code, the table displays 8 columns and the rest are accessible thorugh a scroll bar at the bottm.

My requirement is to stretch the table across the screen so that some more fields are visible.

How do I stretch it across the whole screen so that more fieds are visible?

Thanks,

Ven