Re-sizing of /dev/shm

Is there a way to re-size /dev/shm? I usually have ~400Mb of RAM free and 1G of swap so one would think that /dev/shm would be a nice place for cdbakeoven to create iso-files when burning CD:s. However /dev/shm is something like 200Mb and it doesn't grow wether I burn CD:s or fill it up with zeroes (dd if=/dev/zero bs=1024 count=1000000 of=/dev/shm/nisse).