I just started doing some COBOL code. I just code and transfer from to test environment and then production.
I have no idea how the program works in production.

What I guess is that it's a configuration, like program A can have 10 thousand instances loaded, and if more are requested, the requests enter a queue.
Can the configuration be by program?
For example a withdraw program from a bank. Imagine it has like 50 thousand simultaneous access (between the same second). Is it CICS that handle this?
How it would work in this case? And then if a peak access happens, like 150k/sec?
Could you please share a link that explains how theses multiples online requests are handled?
Thank you!