The documentation refers to AT TLS Support and CBXGSAMP members XCOMTRNG and XCOMTKDB. However, those members don't exist in our environment.
Does this feature need a PTF(s) applied in order to be enabled?
XCOM™ Data Transport® for z/OS 12.0
XCOM r12 added AT-TLS support with fix SO15002 ("ENHANCEMENT: SUPPORT AT-TLS ENCRYPTED NETWORK CONNECTIONS")
For AT-TLS support with XCOM, download the fix and all of the prerequisites to APPLY them.
NOTE: If still on GEN LEVEL 1407 SP00, the best option is to apply level set PTF LU04743 for 12.0.01 (GEN LEVEL 2202) published in February 2022 which would include the ATL-TLS Support PTF SO15002. More details of LU04743 here: XCOM™ Data Transport® for z/OS 12.0 > Release Notes > New Features
For reference here is the XCOM for z/OS Solutions page:
It is normally advised to apply ALL current maintenance to XCOM r12.0, since other enhancements and fixes have been added to the release.
However, if still using OpenSSL on z/OS do not apply LU07625 ("REMOVE OPEN SSL AND ETPKI FROM XCOM ON Z/OS") until OpenSSL is no longer needed. That PTF removes the ability to use OpenSSL.