Hello,
LoGFiles are not organized as the other datafiles.
They are not written with blocks but like a byte-stream.
Another different is that orcale supports morroring for logfiles,
probably due to this feature it is not possible to increase the size?

They way to increase the size is as written.
* add new bigger log-groups
* switch logfile to the new groups
* delete/drop the old groups

Orca