All I can find is this on perldoc:

To create a shared library, the following steps must be performed:

All I can find is this in your original message:

Hi, I have a .pl file Now I have to convert it .exe (to execute on windows ) and .o (to execute on Unix).

And I see no mention of "shared library" here. Also, while this may have something to do with what you asked, I doesn't see why it should necessarily have to.

in particular your implicit claim i.e. that "a .pl file must be converted to .o to be excuted under Unix" is plainly false, not to mention the fact that .pl and .o are "nothing but extensions" and *NIX is much less extension-centric than Windows* are, so that the actual content of such claim is -strictly speaking- empty.