Thanks, roboticus. The DB connection fails with this message: Total Environment allocation failure! Did you set up your DB2 client environment? That's because the webserver account doesn't have the client enviroment set up, even though my account on the webserver does?
Yes, that's what it sounds like. Normally, a webserver account runs with the minimum configuration and permissions required to do the job, to provide less capability for hackers to attack. Once you set up the webserver account with the DB2 client software, you'll probably get further along.