One of the problems I’ve found with using Jenkins is that with it running on Windows or Linux and have lots of plugs. passing parameters around isn’t as simple i would have liked. Depending on where you use the parameter depends on how it should called. Below is a list of locations in Jenkins and how  to call a parameter in it.

Jenkins Location Parameter
GUI Build Steps ${DB}
Windows Batch Command %DB%
PowerShell Plugin $($env:DB)