This parameter specifies the number of pages that the database server process will reserve as private virtual memory, when a database manager instance is started (db2start). If the server requires more private memory, it will try to obtain more from the operating system when required.
This parameter does not apply to UNIX-based systems.
Recommendation: Use the default value.
You should only change the value of this parameter if you want to commit more memory to the database server. This action will save on allocation time. You should be careful, however, that you do not set that value too high, as it can impact the performance of non-DB2 applications.