Thank you very much Patrick Steuer. This certainly helps! I am now also in the progress of building OpenSSL and come across missing "cflags" and the likes so with your config I can hopefully save some time as well as verify what I already use. I will also share my config in the near future once I am getting closer to a successful build. Most of the flags I added in my "OS390-Unix" target are the same or similar to yours. Again, thank you. @Michael Mueller: The zOS system Perl was also below the minimum required Perl version but our system administrator pointed me to using rocketsoftware's Perl 5.24 which he already added to the zOS machine I am using some time ago. I hear mixed opinions regarding rocketsoftware but so far I was able to work with it. Just make sure to adjust your LIBPATH, PERL5LIB and so on to make that Perl work. Just sharing in case you did not yet try that. If you get stuck configuring the new Perl I could share my settings. -- Sent from: http://openssl.6102.n7.nabble.com/OpenSSL-User-f3.html