I can't grasp this shared memory thing.

I currently have 512Mb RAM - and the following.
[root@localhost ~]cat /proc/sys/kernel/shmall
2097152
[root@localhost ~]# cat /proc/sys/kernel/shmmax
33554432
Is it easy for you gurus to tell me what is the max I can increase my shared memory to without killing my Asterisk server (running on same box)
or doesn't it work like that?