What role does a facade pattern play in the Refactor phase of IBM Z Modernization?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'It injects logging and monitoring into every COBOL program without modifying their source'. A facade provides a single, simplified entry point to a complex cluster of COBOL programs, decoupling callers from the internal structure and enabling internal swap to Java without changing the caller. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.