This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
If you use a relative link, the file location will be relative to the present working directory for that JVM (in your case the bin directory). If you provide an absolute path, you can put it whereever you want.
I don't know how well it's supported but I've been able to use system properties to build the path:
In this case the logs are going to the TOMCAT/logs directory.