This article documents IDMS support for z/OS 1.13 and any subsequent unsupported z/OS release.
The original r19.0 cover letter, RI77728, says this:
CA IDMS 19.0 requires z/OS at a version level that is supported by IBM. CA IDMS 19.0 requires functionality first introduced in z/OS V1.13.
z/OS 1.13 has been out of support by IBM since September 30, 2016.
See Product lifecycle for z/OS 1.13.x.
Release : All supported releases.
Component : CA IDMS/DB
Broadcom expects that any supported IDMS release will run successfully on z/OS r1.13 and any later release(s) of z/OS as IBM drops support for them.
However, if a problem arises, the extent to which that problem involves z/OS functionality may inhibit our ability to resolve it.
It is recommended that you upgrade to a supported level of z/OS.