Swap space management would need a large space to explain, because it envolves monitoring, troubleshooting, sizing swapspace and it usually is very close to every part of your systems.  When you need more swap space you could do two thinghs:

* Use some free space on your disk (Create a slice with format and add it to /etc/vfstab, then activate it).

* Use the mkfile utility to create a swap file (this is what i am going to show).

You have to be root to add swap space. (You can do it as non-root user, but i do not recommend it because any other user may overwrite the file)

-bash-3.00# swap -l
swapfile dev swaplo blocks free
/dev/dsk/c0d0s1 102,1 8 1220928 1220928

Look that we only have one swap slice. I want to add more swap space.

-bash-3.00# swap -s
total: 120308k bytes allocated + 21988k reserved = 142296k used, 861252k available
-bash-3.00# mkdir /data2
-bash-3.00# mkfile 512m /data2/swapfile
-bash-3.00# ls -l /data2/swapfile
-rw------T 1 root root 536870912 Feb 9 11:17 /data2/swapfile
-bash-3.00# ls -lh /data2/swapfile
-rw------T 1 root root 512M Feb 9 11:17 /data2/swapfile
-bash-3.00# /usr/sbin/swap -a /data2/swapfile

Now i have more swap space added, 512 MB.
-bash-3.00# swap -l
swapfile dev swaplo blocks free
/dev/dsk/c0d0s1 102,1 8 1220928 1220928
/data2/swapfile - 8 1048568 1048568
-bash-3.00#