z/OS Debugger
A tool for running a program step by step, stopping at chosen lines and looking at the values of its fields.
Also written Debug Tool, Xpediter, debugger, breakpoint
A debugger lets you watch a program run one statement at a time. IBM's is called z/OS Debugger, and was earlier called Debug Tool. Xpediter is another widely used product.
You can set breakpoints, places where the program stops, and when it stops you can look at the value of any field, change values, step through the next few statements, and continue. That turns guessing into watching: you can see exactly which path the program takes through an IF and what each field holds at that moment.
Debuggers work with batch programs, CICS transactions, IMS programs and more. The program usually needs to be compiled with the TEST option, so the debugger can match the machine code to the source lines.
They can be used from a 3270 screen, or from a modern editor such as IBM Developer for z/OS or VS Code. Learning to use the site's debugger early saves a lot of time compared with adding DISPLAY statements and rerunning the job.
Where can I learn this hands-on?
Right here, at ZedBank. You take a junior job at a simulated bank and learn each part of the work by doing it, with Zed beside you. There's nothing to install.
Start at ZedBankRelated
- Compiler optionsSettings that control how the COBOL compiler builds a program, which can change both its speed and its behaviour.
- CompileTurning COBOL source code into machine instructions, checking the syntax and producing a listing of any errors.
- COBOLThe programming language most business logic on the mainframe is written in. Verbose by design, and still running the world's payments.
- CEDFThe Execution Diagnostic Facility: a CICS transaction for stepping through another transaction one CICS command at a time.
- DumpA copy of a program's memory taken at the moment it failed, used to find out why.
- IDzIBM Developer for z/OS: an Eclipse-based development tool for writing, building and debugging mainframe programs on a PC.