The default value of Xmox is incorrect. It states it is same as Xmx, but more precisely it is Xmx - Xmns (total heap size reduced by Nursery minimum size)
While Tenure and Nursery have their own independent maximum sizes of respectively Xmox and Xmnx, also the sum of their current sizes cannot be larger than Xmx at any point of time.
Page containing the error: https://eclipse.dev/openj9/docs/xmo/
The default value of Xmox is incorrect. It states it is same as Xmx, but more precisely it is Xmx - Xmns (total heap size reduced by Nursery minimum size)