Preparing to setup SSL with XCOM for z/OS, and not sure which SSL should be used, IBM System SSL or supplied XCOM modified OpenSSL?
Per this page: XCOM™ Data Transport® for z/OS 12.0 > Release Notes > Obsolete Features
OpenSSL been deprecated for use by XCOM on z/OS. OpenSSL only supports older SSL protocols SSLv3 and TLSv1.0 whereas System SSL supports TLSv1.0, TLSv1.1 and TLSv1.2.
Also, the OpenSSL version shipped with XCOM is back leveled and has not been updated to address vulnerabilities.
Thus it is recommended that IBM System SSL should be used.