COBOLSTACK.COM
//COURSES  EXEC PGM=CATALOG,PARM='ALL'

Course catalog

Labs first, video second. Every course runs on your own private environment in the browser — nothing to install — and every exercise is machine-checked against expected output, so you always know exactly where you stand.

Self-paced available now for CS100 and CS105 — the level-zero path from architecture to your first working COBOL program — and for CS110 COBOL Programming I, CS120 JCL & Batch and the CS170 assembler elective — and, on the IBM i side, for CS201 IBM i (AS/400) Foundations and CS210 RPG Programming I — and for the whole Modernization track, CS500–CS550, eleven self-paced courses from strategy through Java for COBOL developers to core banking in Java — including CS505 Java & COBOL from Zero, the track's own from-zero on-ramp for beginner programmers joining a modernization project — open for enrollment now while their videos are produced. Cohort / corporate courses run instructor-led first; self-paced releases follow as each is recorded. Ops-track courses (CS400+) are delivered through corporate training.

Have a SteelFrame ID? Enroll from your account — free and instant for self-paced courses; cohort courses put you on the waitlist for the next class.

Prefer to watch first? Our free course videos on YouTube ↗ are open to anyone, and they come with hands-on exercises you can follow along with on your own environment — watch the lesson, then do it yourself. Start there, then take a seat when you want the graded labs.

Training a team? Any course here can be customized for a corporate cohort — modules mixed, duration adjusted, labs graded to your shop standards.

Developer workstation with a green-on-black terminal session
—— Course Selection Menu · Enter option ——
  1. 1CS100Mainframe Foundations · Intro · self-paced ~16h (2 days as a cohort)
  2. 2CS105COBOL On-Ramp: Zero to a Working Batch Program · Intro → Core · self-paced ~30h (4–6 weeks at 6h/week)
  3. 3CS110COBOL Programming I · Core · self-paced ~25–30h (5 days as a cohort)
  4. 4CS120JCL & Batch · Core · self-paced ~21h with labs (3 days as a cohort)
  5. 5CS130VSAM & Datasets · Core · 2 days
  6. 6CS140DB2 & SQL on z/OS · Core · 3 days
  7. 7CS150CICS Online Programming · Core · 4 days
  8. 8CS160REXX, CLIST & ISPF Dialogs · Elective · 3 days
  9. 9CS170HLASM: Assembler for Programmers Who Know a Little COBOL · Elective · self-paced ~28h (5–7 weeks at 5h/week)
  10. 10CS200IBM i / AS400 RPG Track · Core · 5 days
  11. 11CS201IBM i (AS/400) Foundations · Intro · self-paced ~6–8h (1 day as a cohort)
  12. 12CS210RPG Programming I · Core · self-paced ~25–30h (5 days as a cohort)
  13. 13CS300The Seam — How Mainframes Talk to Everything Else · Flagship · 5 days
  14. 14CS310ISO 20022 for Payments Teams · Compliance · 3 days
  15. 15CS400Mainframe Operations · Core Ops · 3 days
  16. 16CS410Batch Scheduling Operations (CA-7 & Control-M style) · Core Ops · 2 days
  17. 17CS420CICS Administration · Admin · 2 days
  18. 18CS430z/OS System Programming Foundations · Admin · 3 days
  19. 19CS440IBM i Operations & Administration · Core Ops · 2 days
  20. 20CS450Mainframe & IBM i DevOps · Advanced · 3 days
  21. 21CS460MQ Fundamentals & Administration · Elective · 2 days
  22. 22CS470DB2 for DBAs (Introduction) · Admin · 2 days
  23. 23CS500Modernization Strategy & Approach Selection: Rehost, Refactor, Rewrite, Replace · Intro · self-paced ~14h with labs (2 days as a cohort)
  24. 24CS505Java & COBOL from Zero: Foundations for Modernization Engineers · Intro → Core · self-paced ~120h with labs (12–16 weeks at 8–10h/week; 15 days as a bench cohort)
  25. 25CS510Java for COBOL Developers: the Bridge · Core · self-paced ~30h with labs (5 days as a cohort)
  26. 26CS520COBOL → Java/Spring Modernization Engineer: Refactor to Idiomatic Java, Proven Equivalent · Flagship · self-paced ~42h with labs (7 days as a cohort)
  27. 27CS521Transliteration & Equivalence Engineering: Converting COBOL to Java Byte for Byte, and Working Inside Converted Code · Core · self-paced ~30h with labs (5 days as a cohort)
  28. 28CS525Rewrite & Re-architecture: From Business Rules to Services, Proven by Behaviour · Advanced · self-paced ~35h with labs (6 days as a cohort)
  29. 29CS530Modernization Testing & Equivalence: Old and New Side by Side · Core · self-paced ~20h with labs (3 days as a cohort)
  30. 30CS535Hybrid Modernization & Coexistence: API Enablement, Change Data Capture and the Strangler Fig · Core · self-paced ~20h with labs (3 days as a cohort)
  31. 31CS540Core Banking in Java: Ledger, Posting and End-of-Day · Advanced · self-paced ~40h with labs (7 days as a cohort)
  32. 32CS545Payments & ISO 20022 in Java · Elective · self-paced ~16h with labs (2 days as a cohort)
  33. 33CS550AI-Assisted Modernization with MCP: Verify, Don’t Trust · Advanced · self-paced ~14h with labs (2 days as a cohort)
CATALOG33 COURSESREADY
//PATH    EXEC PGM=LEARN,PARM='LEVEL.ZERO'

Starting from level zero? Architecture first, then COBOL, then build

The most common question we get: "I have a basic idea of what a mainframe is and nothing more — where do I start?" Here is the sequence, in the order the knowledge actually stacks. The first two are self-paced and certificate-bearing; you can start today.

StepCourseWhat it gives youFormat
1CS100 Mainframe FoundationsThe architecture and the key components: hardware, z/OS and address spaces, the subsystem map, datasets and EBCDIC — then TSO/ISPF, the editor, your first job, and a batch program and a CICS screen reading the same record. Certificate: capstone job chain + abend diagnosis + architecture check.self-paced ~16h
2CS105 COBOL On-RampCOBOL from zero, gradually: read a real program, then grow one program through twelve checkpoints into a complete batch application. Certificate: hidden-dataset capstone, byte-checked, craft rules enforced.self-paced ~30h
1–2 alt.CS505 Java & COBOL from ZeroHeaded for a modernization project rather than a maintenance seat? Take this instead of steps 1–2 (and later CS510): both languages taught at once from zero on the CardDemo estate, with beginner JCL, CICS and Assembler blocks built in. Certificate: dual capstone, two reading checks, three beginner gates. Graduates go straight to CS520/CS521/CS530.self-paced ~120h
3CS120 JCL & Batch → CS130 VSAMThe plumbing your program runs in, then make it keyed over VSAM.CS120 self-paced · CS130 cohort
4CS140 DB2 and CS150 CICSThe two subsystems every job posting names beside COBOL and JCL.cohort

Want a faster pace? CS110 COBOL Programming I covers CS105's ground in eight denser sessions — self-paced on video (the capstone videos are coming soon) or as a five-day cohort intensive; either one satisfies the COBOL prerequisite for CS140 and CS150. Budget about six weeks at six hours a week for steps 1–2, then start CS120 self-paced and join the next cohort for CS130.

Heading for the midrange instead? The same level-zero sequence exists for IBM i (AS/400): CS201 IBM i (AS/400) Foundations (self-paced, about 6–8 hours, all 15 videos recorded) and then CS210 RPG Programming I (self-paced, about 25–30 hours; Sessions 1–5 recorded, the rest released session by session). CS200 is the five-day cohort intensive on the same track: it covers that ground faster and continues into display files and subfiles, CL programming, ILE and embedded SQL — take it as a team, or after CS210 for the sessions CS210 does not reach.

//MODERN   EXEC PGM=MIGRATE,PARM='CARDDEMO.TO.JAVA'

Modernization track: the mainframe running beside its Java replacement

Every course in this track runs the AWS CardDemo application live on SteelFrame — its COBOL, JCL, CICS screens and VSAM/DB2 data — and puts it beside the Java that replaces, wraps or converts it. Nobody else can show the legacy side working in the same frame as the new one; every lab starts on the mainframe to produce the golden and ends when the Java matches it. One shared hallway, then a door per conversion style — because "COBOL to Java" is at least five different jobs with five different definitions of done.

StepCourseWhat it gives youFormat
HallwayCS500 Strategy & Approach SelectionNine styles in three families, chosen per application from the estate’s own inventory, graph and run data; cost, lock-in, the failure cases; an assessment pack on a hidden estate.self-paced ~14h
On-rampCS505 Java & COBOL from Zero From zeroFor beginner programmers assigned to a modernization bench: both languages in lockstep, one idea per video in both forms, every claim proven against CardDemo running live; JCL, CICS and Assembler basics placed where you need them; a dual capstone. Replaces CS105 + CS510 for a from-zero student. Second to be released.self-paced ~120h
HallwayCS510 Java for COBOL Developers: the BridgeJava 21 one COBOL idea at a time, each proven against the COBOL original: CBACT01C rebuilt as a Java report, byte for byte. First to be released.self-paced ~30h
HallwayCS530 Modernization Testing & EquivalenceThe verification half: fixtures, goldens, batch/screen/data equivalence, parallel run, an auditor-grade evidence pack; five seeded defects to find.self-paced ~20h
Door 1CS520 Modernization Engineer: refactor to idiomatic Java FlagshipCardDemo rebuilt as Spring Boot + Spring Batch + PostgreSQL in six waves, each proven equivalent through a governed rules file; CI, containers, domain model, events.self-paced ~42h
Door 2CS521 Transliteration & Equivalence EngineeringConvert byte for byte over an open emulation runtime with zero declared differences; remediate what the tool could not do; work inside generated code.self-paced ~30h
Door 3CS525 Rewrite & Re-architectureRules extracted from the running COBOL into a register, a Spring domain built to them, parity proven by behaviour contracts, one function strangled.self-paced ~35h
Door 4CS535 Hybrid Modernization & CoexistenceThe mainframe stays the system of record: CICS programs as APIs, events over MQ, change capture into a replica, routing with rollback, reconciliation.self-paced ~20h
Bank sideCS540 Core Banking in Java and CS545 Payments & ISO 20022 in JavaA ledger, posting and end-of-day core proven to the cent against CardDemo’s cycle, integrated with a packaged core (Apache Fineract); ISO 20022 messages out of and into the same records.self-paced ~40h · ~16h
Governed AICS550 AI-Assisted Modernization with MCPAn agent on the SteelFrame MCP under scoped tokens: it types, the oracle judges, you govern; the five failure sites as drills.self-paced ~14h

Paths: beginner programmer → modernization bench (CS505 → CS520 / CS521 / CS530); COBOL developer → modernization engineer (CS510 → CS520 → CS530); conversion engineer (CS510 → CS521 → CS530); rewrite engineer (CS530 S1–3 → CS525); integration engineer at a bank that keeps the mainframe (CS535); Java developer → new core (CS540 → CS545); leads and architects (CS500). The track’s data course, CS565 Data Migration & Reconciliation, ships with the data track. Paid individual on this track is $349 per course, one-time; the Free individual plan is open on every course now.

//LEARN    EXEC PGM=DOING,PARM='TRY.BREAK.FIX'

Learn by doing, on a real environment

You do not learn a mainframe by watching one. From the first session you are logged on to your own mainframe-compatible environment in the browser — datasets to allocate, jobs to submit, abends to read, programs to fix. You touch the system; the video only shows you where to put your hands.

The fastest way to real skill is the loop every working mainframer already knows: try it, break it, fix it. Our courses are built around that loop. Each exercise gives you something to run, something that goes wrong, and the means to find out why — on an environment where a mistake costs a reset, not a batch window. Learners who have already made the mistakes safely are the ones who are productive when it counts.

Try
Submit the job, run the transaction, issue the command — yourself, on your own environment, from the first session. Nothing to install.
Break
Exercises go wrong the way real work goes wrong: a record length that does not match, a sign nibble, a missing DD. You see the abend, not a slide of it.
Fix
Read the message, correct the code, resubmit. The lab harness checks your output against the expected result, so you know the moment it is right.

The free course videos ↗ teach the same way: each lesson pairs with a hands-on exercise to follow along with on your own environment. The environments page describes what that environment is — and, honestly, what it is not.

//FLAGSHIP DD DSN=CS300.SEAM,DISP=SHR

Why CS300 exists

Nobody teaches how a mainframe hands data to a relational database at end of day, what copybook-to-column mapping actually involves, or why the packed-decimal sign nibble matters — because teaching it requires both platforms side by side. That's the unhireable skill in banking IT, and it's a five-day course here, taught on a mixed estate that ships broken on purpose: one real production defect class per lab.

The Seam — full syllabus