In which directory should the pcre archive be unpacked for assembly?

Question

Nginx

I need to build the pcre library in order to build nginx. Reading the obvious in mana for building a regular expression library

tar zxvf pcre-8.37.tar.gz
cd pcre-8.37

And then the question arises, where exactly is it in which directory to unpack the pcre archive.
And again the question is, where do I need to unpack the archive with nginx for assembly? And it's not entirely clear what to do with the nginx-1.12.2.tar.gz.asc file?