If this option is enabled, all of the builds that are referenced from builds of this project (via fingerprint) will be protected from log rotation.

When your job depends on other jobs on Jenkins and you occasionally need to tag your workspace, it's often convenient/necessary to also tag your dependencies on Jenkins. The problem is that the log rotation could interfere with this, since the build your project is using might already be log rotated (if there have been a lot of builds in your dependency), and if that happens you won't be able to reliably tag your dependencies.

This feature fixes that problem by "locking" those builds that you depend on, thereby guaranteeing that you can always tag your complete dependencies.