There is a function in Perl named PerlEnv_getenv() which is equivalent to getenv() in C. It invokes the environment variable. It uses the library the library perlclib.How to define this library and use the Perl function?
I took this example from the net :
C: currentpath = getenv("PATH"); => in Perl: $currentpath = $ENV{PATH};
Besides that, you can install additional module which provides Perl API for getenv - CPAN powered.
Just to paraphrase, in Perl, you access the environment through the %ENV hash.
If you are not trying to write a program in Perl, then obviously you have the Perl source code, which is where this function is defined; compile it into a library, and put it where the linker can find it. I don't think it's meant to be used by code outside of Perl itself so you probably won't be able to find general-purpose documentation for it.
If this didn't answer your question, then perhaps you could describe what you are trying to accomplish.