It is desirable to declare standard libraries available on a given system.
Putting target declaration in a specific project's Jamfile is not really
good, since locations of the libraries can vary between different
development machines and then such declarations would need to be
duplicated in different projects. The solution is to declare the targets
site-config.jam configuration file:
project site-config ; lib zlib : : <name>z ;
Recall that both
user-config.jam are projects, and everything you can
do in a Jamfile you can do in those files as well. So, you declare a
project id and a target. Now, one can write:
exe hello : hello.cpp /site-config//zlib ;
in any Jamfile.