Mainframe engineers for the z/OS estate you actually run.
We upgrade z/OS, keep CICS and IMS current, clean up RACF and staff the systems programming and COBOL skills that are hard to hire. Modernization starts from what the code does today, not from a slide.
Cohash supplies certified mainframe engineers for IBM Z.
We upgrade z/OS to 3.1 or 3.2, migrate CICS TS and IMS, clean up RACF, maintain COBOL and recompile it on Enterprise COBOL 6, and put APIs in front of tested transactions. Engineers work onsite in the US, nearshore or offshore, on contract, contract-to-hire or permanent terms. Sites still on z/OS 2.5 now depend on IBM's service extension, so the 3.x plan usually comes first.
you probably need this if
The z/OS 2.5 support date passed and the 3.x upgrade still has no booked window.
Only one person understands the SMP/E zones, and they are planning to retire.
Auditors keep finding RACF profiles with UACC(READ) or ID(*) on production datasets.
LPAR and product inventory with every blocker to z/OS 3.2 marked
ISV compatibility matrix with vendor support statements per product
Sandbox upgrade runbook with step timings and fallback IPL plan
+ 3 more documents
who does it
z/OS systems programmer (SMP/E, parmlib, IPL)CICS TS systems programmerIMS DBA and systems programmer
IBM Mainframe Systems Programmer Certificate
IBM Mainframe RACF Security Administrator Certificate
13 Jun 2025IMS 15.6 generally available First IMS release that requires managed ACBs before migration. Sites staying on 15.5 should not apply the 15.6 release marker PTFs. source ↗
05 Sep 2025CICS TS 6.3 generally available Adds Java 21, Jakarta EE 10, Spring Boot 3, native OpenTelemetry tracing, YAML-based region configuration and an MCP server for CICS region data. source ↗
30 Sep 2025z/OS 3.2 generally available Announced under AD25-0005. IBM puts it on the Enhanced lifecycle policy, which means at least five years of support plus a three-year extension. source ↗
01 Oct 2026z/OS 2.5 moves to service extension IBM's service extension table lists new and known defect support for z/OS 2.5 from 1 Oct 2026 to 30 Sep 2029. source ↗
today · Oct 22, 2026
the story · ibm z mainframe estate
From the first call to a setup your own team can run.
Here's what usually prompts a call about your IBM Z Mainframe estate, what we do about it and in which order, and where you end up.
01 · where it hurts02 · what we change03 · how it runs04 · where you end up
incident board · ibm z mainframe estate3 open
openThe z/OS 2.5 support date passed and the 3.x upgrade still has no booked window.
recurringOnly one person understands the SMP/E zones, and they are planning to retire.
blockedAuditors keep finding RACF profiles with UACC(READ) or ID(*) on production datasets.
exposure
z/OS upgrades to 3.1 and 3.2CICS TS and IMS migrationsRACF administration and clean-upCOBOL maintenance and compiler…Modernization through APIs and…Mainframe staffing
z/OSB2Bi
startrehearsehandover
Estate inventory
Sandbox build and rehearsal
Staged rollout
Handover and staffing
we are here
ready to hand over
Production reaches a supported z/OS release on a rehearsed plan, and knowledge of the…
Managed ACBs go live in production ahead of the version change.
LPAR and product inventory with every blocker to z/OS 3.2 marked
ISV compatibility matrix with vendor support statements per product
chapter 01 · where it hurts
Why teams reach out
The z/OS 2.5 support date passed and the 3.x upgrade still has no booked window.
Only one person understands the SMP/E zones, and they are planning to retire.
Auditors keep finding RACF profiles with UACC(READ) or ID(*) on production datasets.
chapter 02 · what we change
How we solve it
z/OS upgrades to 3.1 and 3.2
CICS TS and IMS migrations
RACF administration and clean-up
COBOL maintenance and compiler upgrades
Modernization through APIs and selective rewrites
Mainframe staffing
chapter 03 · how it runs
Our approach
Estate inventory
Sandbox build and rehearsal
Staged rollout
Handover and staffing
chapter 04 · where you end up
What changes
Production reaches a supported z/OS release on a rehearsed plan, and knowledge of the SMP/E environment lives in runbooks and in more than one head.
Managed ACBs go live in production ahead of the version change.
LPAR and product inventory with every blocker to z/OS 3.2 marked
ISV compatibility matrix with vendor support statements per product
what we do
Our IBM Z Mainframe work
6 kinds of IBM Z Mainframe work, each run by engineers who have done it on live tenants.
Driving-system and target-system planning, a sandbox LPAR rehearsal, system health checks before and after, and a tested fallback IPL. ISV products are checked for 3.x support before the window is booked.
CICS TS 6.3 upgrades with a review of SIT overrides, CSD groups and Java workloads. IMS 15.6 migrations, which need managed ACBs in place before the release marker PTFs go on.
Dataset and general resource profile review, UACC and ID(*) access, revoked and unused user IDs, started task identities and the SETROPTS options auditors ask about.
Enhancements and fixes in COBOL, PL/I, JCL and Assembler, plus Enterprise COBOL 6 recompiles with regression tests aimed at the behavior changes between compiler releases.
REST APIs in front of CICS and IMS transactions so new channels reuse tested logic. Where a rewrite is justified, we carve out one bounded function at a time with parallel runs against the original.
Systems programmers, CICS and IMS specialists, RACF administrators and COBOL developers. Onsite in the US, nearshore or offshore, on contract, contract-to-hire or permanent terms.
capability 01 / 06in production
z/OSB2Bi
z/OS upgrades to 3.1 and 3.2
Driving-system and target-system planning, a sandbox LPAR rehearsal, system health checks before and after, and a tested fallback IPL. ISV products are checked for 3.x support before the window is booked.
CICS TS 6.3 upgrades with a review of SIT overrides, CSD groups and Java workloads. IMS 15.6 migrations, which need managed ACBs in place before the release marker PTFs go on.
Dataset and general resource profile review, UACC and ID(*) access, revoked and unused user IDs, started task identities and the SETROPTS options auditors ask about.
Enhancements and fixes in COBOL, PL/I, JCL and Assembler, plus Enterprise COBOL 6 recompiles with regression tests aimed at the behavior changes between compiler releases.
REST APIs in front of CICS and IMS transactions so new channels reuse tested logic. Where a rewrite is justified, we carve out one bounded function at a time with parallel runs against the original.
Systems programmers, CICS and IMS specialists, RACF administrators and COBOL developers. Onsite in the US, nearshore or offshore, on contract, contract-to-hire or permanent terms.
We pieced these together from IBM Z Mainframe situations that come up a lot. They're patterns. You won't find a specific client in them.
case file 01
z/OS 2.5 past base support, six LPARs and one retiring sysprog
composite · not a client story
Beforethe situation
Six LPARs across two sysplexes still run z/OS 2.5. Base support ended in September 2026, about forty ISV products sit on top, and the one systems programmer who knows the SMP/E zones retires next year.
What we dothe work
We inventory every ISV product and collect each vendor's 3.2 statement first. A sandbox LPAR gets z/OS 3.2 with timings recorded, then test and development LPARs follow. A second engineer shadows the retiring sysprog and documents the zones as the work runs.
Afterwhere you end up
Production reaches a supported z/OS release on a rehearsed plan, and knowledge of the SMP/E environment lives in runbooks and in more than one head.
case file 02
IMS 15.5 with DBDs and PSBs still built the old way
composite · not a client story
Beforethe situation
IMS 15.5 runs core policy databases, with ACBs still generated by ACBGEN. The 15.6 upgrade is on the roadmap, but nobody has tried managed ACBs and the DBA team is two people.
What we dothe work
We copy the IMS catalog setup to a test system, switch it to managed ACBs and run the online and batch regression there. Then we plan the production cut-over, and only after it is stable do the 15.6 release marker PTFs go on.
Afterwhere you end up
Managed ACBs go live in production ahead of the version change. So the 15.6 migration turns into routine maintenance, with no second change stacked on top of it.
We don't start a step until the last one has produced something you can check.
step 01
Estate inventory
We list LPARs, sysplexes, product levels, ISV software, compiler levels and RACF settings, then mark what blocks a move to z/OS 3.2 or the next CICS and IMS release.
step 02
Sandbox build and rehearsal
The new z/OS level is built and IPLed on a sandbox LPAR. Health checks run, ISV products start, and batch and online regression runs with timings recorded.
step 03
Staged rollout
Test, then development, then production LPARs, each with a fallback IPL plan. CICS and IMS changes follow in their own windows so problems stay easy to isolate.
step 04
Handover and staffing
Your team gets the runbooks, updated SMP/E documentation and a skills map. If gaps remain, we place engineers onsite, nearshore or offshore to cover them.
ai on ibm z mainframe
Where AI fits on IBM Z Mainframe, and where it needs guardrails.
IBM ships AI at three levels on Z: watsonx Code Assistant for Z for explaining and transforming COBOL, the Telum II on-chip AI accelerator in z17 for inference near the data, and an MCP server in CICS TS 6.3 for region data. Most teams start with code understanding, because that's where the skills gap hurts.
AI agentasks for data or an action
Scoped identityonly the access it needs
MCP serverthe one door into the platform
Logged, approveda person signs off on writes
z/OSIBM Z Mainframedoes the work
CICS TS 6.3 ships with an MCP server, but it covers CICS region data. Transactions are a different matter. There, agents should call REST APIs that sit in front of CICS or IMS. Give each agent its own RACF user ID with minimal access, keep SMF logging on, and have a person approve any update.
watsonx Code Assistant for Z
It explains COBOL in plain language and refactors COBOL and PL/I into modular services. It can transform COBOL to Java too, and generate unit tests comparing the two. For us the first use is documenting programs. Then we transform one bounded function and run it in parallel against the original.
AI on z17 hardware
z17 runs on Telum II, which has a second-generation on-chip AI accelerator for low-latency inference. For generative AI, IBM added the Spyre Accelerator card. For us the question is where scoring inside CICS or batch beats sending data off the platform.
Operations and incidents
IBM says watsonx Assistant for Z integrates with Z Operations Unite for chat-based incident detection and resolution. Z Operations Unite gathers metrics and logs across IBM Z. For us the work is hooking up your SMF and log sources, and setting what the assistant may suggest.
CICS TS 6.3 MCP server
CICS TS 6.3 adds an MCP server for CICS region data, so agents can read region information without screen-scraping. We put it behind RACF-controlled IDs and start read-only.
How IBM Z serves digital channels, partners and analytics
Web and mobile apps get to CICS and IMS transactions through a REST API layer, and partner files come in through batch. Every access goes through RACF. SMF records feed the SOC, and governed copies of the data go out to the warehouse.
01 · Channels
Web and mobile appscustomer · agent desktop → REST API layer · REST/JSON→ IBM MQ · async requests
B2Bi
Partner filesEDI · SFTP → Batch · inbound files
02 · Integration
REST API layerJSON to COMMAREA · OAuth → z/OS 3.2 LPARs · transaction call
IBM MQqueues · triggers → z/OS 3.2 LPARs · messages
These are working documents, written against your configuration, so your team can run them without us.
inventory01
LPAR and product inventory with every blocker to z/OS 3.2 marked
yours to keep
document02
ISV compatibility matrix with vendor support statements per product
yours to keep
runbook03
Sandbox upgrade runbook with step timings and fallback IPL plan
yours to keep
report04
RACF exposure report ranked by UACC, ID(*), WARNING mode and unused IDs
yours to keep
report05
Managed ACB readiness assessment for the IMS 15.6 migration
yours to keep
inventory06
Skills map of who knows what, with cover for single points of failure
yours to keep
talent and delivery · ibm z mainframe
Certified engineers, wherever you need them.
Some clients want a project team, some want a couple of engineers on theirs. Either works. Onsite, nearshore or offshore, with handovers across time zones that keep things moving.
Put these to anyone bidding on your IBM Z Mainframe work. The ones who've done it answer differently from the ones who've read about it.
Q1
Which of our ISV products have published support for z/OS 3.2, and who chases the rest?
Vendor software is usually what delays a z/OS upgrade. A partner should build the matrix and own the follow-up with each vendor before the window is booked.
Q2
How will you test managed ACBs before we touch IMS 15.6?
IBM requires managed ACBs before migrating to IMS 15.6. Doing that switch and the version change in one window stacks two risks together.
Q3
What is your fallback if the new z/OS level fails to IPL cleanly?
A tested fallback to the previous IPL volumes and parmlib members is the difference between a long night and an outage. Ask to see it rehearsed.
Q4
How do you find RACF profiles that grant more than they should?
UACC settings, ID(*), WARNING mode and orphaned IDs hide easily in a big RACF database. Auditors trust reports pulled from the database itself and ranked by exposure.
Q5
Who on your team has run CICS TS 6.3 with Java workloads in production?
CICS TS 6.3 adds Java 21, Jakarta EE 10 and Spring Boot 3 support. If your regions run Java applications, the JVM server changes are where the upgrade tends to bog down.
01Is z/OS 2.5 still supported?
IBM's lifecycle moved z/OS 2.5 off base support at the end of September 2026. IBM's service extension table lists new and known defect support for 2.5 from 1 October 2026 to 30 September 2029, under a separate agreement. That buys time, but new function and full support are on 3.x, so we treat 2.5 as a migration deadline.
02Should we go to z/OS 3.1 or straight to 3.2?
Usually 3.2. IBM withdrew z/OS 3.1 from marketing on 26 January 2026, and 3.2 has been generally available since 30 September 2025. The real constraint is ISV software: we inventory every vendor product and check its 3.2 support statement before committing to a target.
03How long does a z/OS upgrade take?
It depends on how many releases you skip, how many LPARs and sysplexes you run, and how much ISV software needs new levels. We build and IPL a sandbox first, time each step, and set the production schedule from that rehearsal rather than from a template.
04Can you convert our COBOL to Java?
We can, but we rarely start there. Most estates get more from putting APIs in front of stable transactions and rewriting the few functions that change often. If conversion is the goal, we pick one bounded function, run it in parallel with the COBOL original and compare outputs before going further.
05Do you provide mainframe staff as well as projects?
We do. Certified systems programmers, CICS and IMS specialists, RACF administrators and COBOL developers can all be placed. They work onsite in the US or from nearshore and offshore, across all time zones, and on contract, contract-to-hire or permanent terms.
06Can you prepare RACF for an audit?
Yes. We pull the RACF database into reports, rank profiles by exposure (UACC, ID(*), WARNING mode, unused IDs) and fix the worst first with change records your auditors can follow.
services
Related services
Projects on IBM Z Mainframe usually end up touching one of these, so they're worth a look.
