In recent versions, z/OS has been copying lots of Linux-specific APIs (e.g. unshare [0]) in order to support the z/OS port of Kubernetes.

If Kubernetes starts using renameat2(RENAME_EXCHANGE), they could very plausibly add it.

[0] https://www.ibm.com/docs/en/zos/3.2.0?topic=csd-unshare-bpx1...

pedantic but z/OS isn't a unix, it can just pretend to be one enough for the open group to call it one. IBM has a unix still, AIX.