> libpng needs -lpng16 and -lz Where? I'm compiling the same program with exactly the same makefile on several linux distributions, openbsd, freebsd and macos

> libpng needs -lpng16 and -lz Where? I'm compiling the same program with exactly the same makefile on several linux distributions, openbsd, freebsd and macos and "-lpng" is all it needs. This is for dynamic linking. For static linking I need to add -lz explicitly, you are right about that.