I do not think that increasing the size of /run is necessary, but in case you do need to increase it try editing your /etc/fstab file. All mountpoints and most partitions are listed there. If your /run partition is a tmpfs(which it should be, at least according to http://askubuntu.com/questions/57297/why-has-var-run-been-migrated-to-run, I would confirm before following these instructions) then you can simply change the fstab line of your /run mount to something akin to the following:
none /dev/shm tmpfs defaults,size=8G 0 0
See how the size is declared right after
defaults? Try doing that. You can use megabytes as well by using M:
none /dev/shm tmpfs defaults,size=100M 0 0
Reboot the computer after this and the changes should take place.
Edit: Scratch that, looks like Ubuntu creates the
run partition using files in /etc/init and /etc/init.d and not via fstab. You'd have to look through those files and find the mount command that it uses to create
run and edit it manually. I don't have a box to test this on right now, but try running this:
find /etc/init* -type f | xargs grep "mount"
find /etc/init* -type f | xargs grep "run"
If it's being mounted via a bash script then this should find the file and line that does the mounting.