如何获取php.exe驻留在php.ini中的目录

So I need to save the session files in a path that lies inside directory where php.exe is residing.

So in case if php.exe is in: D:\scripting\php5\ I need the session files to be in D:\scripting\php5\session\ but if I move the php5 directory anywhere else in the disk and run php.exe from there I want the location of session files change accordingly. So is it possible to establish location of php.exe using any built in variable in php.ini ?