How can I see variable's values in another subfunction?

I have a main function. The main function calls two subfunction sub_A and sub_B.And sub_A calls sub_C,sub_B calls sub_D. The question is if I stop in sub_D in debug mode and want to check a variable's value in sub_C, how can I do that? I know dbup and dbdown, but it seems only can check up and down in the same call stack. And what I figure out now is adding 'disp' in sub_C. Is there any way more elegance? Thanks for any advice.