The amount of memory required per user connection varies by platform, and it changes when you change other configuration variables, including:
default network packet size
stack size and stack guard size
user log cache size
Changing any of these parameters changes the amount of space used by each user connection: multiply the difference in size by the number of user connections. For example, if you have 300 user connections, and you increase the stack size from 34K to 40K, the new value requires 1800K more memory.
