tuning Postgres Centos 5.6 with 64gb memory shmall

Question

I am trying to tune a 64 bit centos 5.6 Postgres server with 64gb of memory. I am trying to find out the optimal settings for shmall and shmmax.

$ getconf PAGE_SIZE
4096

I also see that Hugepagesize is supported, but not sure how to factor that in:

$ cat /proc/meminfo |grep Hugepagesize
Hugepagesize:     2048 kB