How can I specify libraries for gcc via the PATH variable

I want to use the python boost library. I am using a compiler gcc. The path variable in Windows shows the paths to the boots main folder. Can I use this or another system variable to specify the paths to the libraries for the compiler? (I also have a variable BOOST_ROOT, which also shows the path to the root folder of boost.) (I use gcc from console)

I know, that i can use this line:

-L/usr/local/boost/boost_1_39_0/stage/lib

But i have not "stage" directory.