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Mainframe (z/OS, COBOL, copybooks and JCL)

What the Editor's Mainframe module does for z/OS application programmers and production support, which IBM and vendor engines it drives through z/OSMF, how it starts, and exactly what has and has not been verified.

The Mainframe module brings the loop of ISPF, SDSF and IBM Developer for z/OS (IDz) into the Editor: edit a member, compile it with the shop's procedure, read the listing, submit the batch job, find the failing step in the spool, map the abend to the source line, and look at the data through its copybook.

The engines stay the shop's own, driven through z/OSMF: Enterprise COBOL and the binder through your cataloged procedures, JES for submit, status and spool, the Db2 precompiler or coprocessor with BIND, the CICS translator, IDCAMS, DFSMShsm, SDSF's REXX interface, CICS through CMCI, Endevor Web Services and IBM z/OS Debugger in batch mode. Nothing needs to be installed on z/OS beyond z/OSMF, and nothing but the Editor on the workstation.

GnuCOBOL, GDB and COBOL Check on the workstation are an optional second path, for continuous integration and for engineers without a host seat. Their results are GnuCOBOL's, not Enterprise COBOL's, and every surface that shows them says so.

Verification state: read this first

Nothing in this module has run against a z/OS system yet. Every z/OS capability is tested against a local HTTPS server shaped like z/OSMF (real TLS, behaviour modelled from IBM's documentation and the Zowe SDK), or against fixtures written to IBM's documented formats. A verification kit lets you run the module's exact requests on your own z/OS; no run has come back yet.

DimensionVerifiedNot yet verified
z/OS and its productsNone. A local z/OSMF-shaped server and documented-format fixturesAny z/OS, z/OSMF, JES, Enterprise COBOL, Db2, CICS, API Mediation Layer, TSO/E, SDSF, Endevor, DBB or z/OS Debugger level
Operating systemsLinux only (Ubuntu 24.04, x86-64), for the tests and the running appWindows and macOS
Workstation toolsGnuCOBOL 3.1.2 (BDB indexed handler), GDB 15.1, COBOL Check 0.2.19 with Java 21GnuCOBOL 3.2; other GDB and COBOL Check versions
TN3270The 3270 emulator against Hercules 3.13 (a real TN3270 server, not z/OS)A z/OS TN3270 server; ISPF, SDSF, CICS, IMS or z/OS Debugger screens
ProjectsThe payroll sample; AWS CardDemo (44 programs, 62 copybooks, 55 jobs); IBM's dbb-zappbuild MortgageApplication; a generated estate of 37,601 membersA customer's repository

Language features, the application map, code review, data flow and the Record Viewer are our own code and are verified on Linux on those projects. Do not rely on a z/OS capability for production work until it is verified on your z/OS and z/OSMF levels.

How the module starts

The module has two sides. Both run only in a trusted window (a window without a folder counts as trusted unless security.workspace.trust.emptyWindow is off) and while neuralInverse.mainframe.enabled is not false (it is true by default).

  • z/OS side: runs while a z/OS connection exists, either a z/OSMF profile of your Zowe team configuration or a connection added in the Editor, with or without a folder. An engineer whose source lives in PDS libraries, Endevor or ChangeMan can open an empty window and work with data sets, jobs, spool, search, z/OS UNIX files and TSO/E.
  • Project side: runs while a workspace folder holds a Mainframe project: mainframe.json, a ZAPP file, zAppBuild's application-conf/application.properties, or COBOL, copybook, JCL or procedure members, found up to twelve folders deep.
  • Both: COBOL and JCL language features, column editing, the record editor, the job editor and the walkthrough run while either side runs. Compile on z/OS and Check on z/OS need both.

COBOL and JCL colouring and the mainframe.json schema are always available.

When the project sets host.compile and a connection exists, z/OS leads: the build key (Ctrl+Shift+B) and the first title bar button run Compile on z/OS. Otherwise the GnuCOBOL loop leads.

A project opened without a z/OS connection: the empty editor offers the GnuCOBOL actions and Connect to z/OS.A project opened without a z/OS connection: the empty editor offers the GnuCOBOL actions and Connect to z/OS.

Where things appear

SurfaceWhat
Title barCompile on z/OS, Submit JCL to z/OS and Show z/OS Jobs while z/OS leads; then Run JCL with GnuCOBOL and Debug JCL Step with GnuCOBOL
Explorer, z/OS Data Sets viewConnections, data sets and members, z/OS UNIX paths, VSAM clusters, CICS regions, debug profiles, host projects
Explorer, Mainframe Application viewJobs, programs, copybooks, data sets and Db2 tables, and how they connect
EditorsMembers as COBOL or JCL (zosmvs:), spool files read-only, the job editor, the Record Viewer, the 3270 session, SDSF panels, control flow and data flow
ProblemsCompiler messages from z/OS (IGY, DSNH, DFH, DSNT), live COBOL checks, JCL problems, IDCAMS and utility messages, GnuCOBOL messages
TerminalThe TSO/E terminal, "TSO: <profile>"
Status barThe connection the active file uses and its state; workstation tools, only when one is broken
Welcome page"Get Started with z/OS, COBOL and JCL"; each step checks off only on its real outcome

Commands are in the Command Palette under Neural Inverse Mainframe.

The Get Started with z/OS, COBOL and JCL walkthrough with a project open, z/OS steps first and the GnuCOBOL steps optional.The Get Started with z/OS, COBOL and JCL walkthrough with a project open, z/OS steps first and the GnuCOBOL steps optional.

Pages in this section

Set up

Data on z/OS

Source

Understand the application

Run on z/OS

The workstation path

Reference

Last reviewed 18 October 2026View as Markdown

Mainframe (z/OS, COBOL, copybooks and JCL) · Docs · Neural Inverse