Hello Manoj,
You can use OS level tools to check RAM and SWAP space, for example 'nmon' or 'top' (topaz) which can show the allocated amount.
If you have 'nmon' then type in 'nmon' followed by typing 'm' which will show the RAM and SWAP allocated.
The allocation you will see is only for the host, to understand how much RAM is allocated for SAP and DB you will have to check the memory parameters.
For SAP check the memory parameters like Ztta* and em*, etc., for more information look into below URL.
Functions of the SAP Memory Management System - SAP Memory Management (BC-CST-MM) - SAP Library
Please note extended memory in SAP uses SWAP space.
There are several SAP notes explaining the memory settings for DB2, similar note is mentioned below.
899322 - DB6: DB2 9.1 Standard Parameter Settings
Thanks.
Regards,
Yoganand.V