How to choose STL library?

[Liu, Guangsheng]

Hi, 
  There are variety of STL implementation.  Currently, I am using RedHat
6.2, gcc 2.95.2, libc.so.6.  I can include something like <map> <vector> and
build it with no special option with g++. It works,  what this really means
to me.  Does this mean the STL implementation is inside libc.so.6, or gcc
compiler somewhere. 
  By the way, I know stdc++ is implementing STL (part of C++ standard). Does
this mean that I can replace stdc++ with libc.so.6 (assuming libc.so.6
implementing STL) in order to use STL inside stdc++? and how?
  Many thanks.