Parameter rdisp/core_file_size value to be changed

Dear Experts, we have a Netweaver 7.5 system. Here one of the Parameter is rdisp/core_file_size. In my system by default the parameter value is "default",but I didn't get any information regarding the size of Default value.If i want to change this parameter how much maximum I can assign . I wasn't find any document related this in Market place. Please give me inputs regarding this parameters like Snote numbers.Thanks in Advance.

Pratapkumar.