How to avoid scrollbar space while its not appear in extjs grid pannel?

Question

Hi in my java project we have extjs grid. while i increase data in grid pannel automatically vertical scrollbar will come.if the data is small amount the scrollbar will not appear. but the space of scrollbar is appeared in my grid. What i need is while data amount is small it shouldnot show scroll bar and scrollbar space, and when i incease the data it should allow the scrollbar to appaear. How can i achive it.

Thanks,