Comment 3 for bug 1564475

128MB is just a sensible default enabled by default everywhere, if in your case you need more do adjust it accordingly in /etc/zipl.conf and execute `sudo zipl` and then reboot.

There is no dynamic sizing / computation of zipl.conf and/or crashkernel paramemter on Ubuntu, and on all architectures one may need to adjust it to lower/higher values as needed.