This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Yes, all connection pools allow to set a minimum and maximum pool size (as well as some other options). Check the documentation of whichever one you're using (Apache DBCP has recently come back to life).