heap size!

I'm a new guy to this field and I'm learning a lot about UNIX! Can any explan to me what exactly does 'heap size' mean and how can i increase the size for AIX 4.3.3?

Found the following at
heap - In programming, the common pool of free memory available to the program.

Some info on heaps ]

Redbooks info

Heap space - scratch, or memory allocated by malloc() is allocated from anonymous memory and mapped read/write.

Look at the /etc/security/limits for the apropiate changes.

Good luck. Hugo.

Note: If you use oracle or DB2 look at www.redbooks.ibm.com
for "Database Performance on AIX
in DB2 UDB and Oracle Environments" SG24-5511-00