True striping is most beneficial when you're doing large sequential reads or writes.
I'm guessing he's got a 36G disk and wants to figure out how to use it best.
tsuba: if you've got just one 36G disk, it doesn't really matter terribly much how you slice it up - you only have one path for data to move through.
If you have multiple disks, you want to spread your data across them as much as you can to distribute the slowest part of the system - the actual reading and writing. AIX's LVM is sufficient for doing this, just create your LVs to use the maximum number of PVs.
Now, from another point of view, I would still create multiple smaller filesystems instead of a single large filesystem. It's probably a personal preference, but I find smaller filesystems easier to manage than large ones, so I cap mine at 8G.