What is a "call level" when talking about scope (OVRDBF/OVRPRTF)?

[JustPassing]

Hi,

I've been programming for a few years now but I've never understood the concept of "call level" as it pertains to OVRDBF/OVRPRTF (OVRSCOPE parameter). The IBM doc just says :

All open operations done at a call level that is the same as or higher than the current call level are influenced by this override.

But what IS a call level? How do I know what call level I'm at? I can't seem to find any straightfoward definitions or explanations so either I'm not looking with the right terms or it's a concept that's (supposed to be) obvious for most people. A concrete example might help me understand the concept.

Thanks.

[B.Hauser]

Call Stack Entry!

[JustPassing]

Thanks ! IBM should perhaps think of linking to that concept on the pages where call level is used.