Mission-Critical Modernization & Software Development on the Z & I
System/77 engineers mission-critical modernization and custom software for IBM z/OS mainframes (zSeries) and IBM i midrange (iSeries / AS/400). We refactor and preserve billions of lines of core business logic across COBOL, HLASM, PL/I, RPG, and REXX with guaranteed semantic equivalence.
zSeries & iSeries Modernization
Open up isolated mainframe and midrange silos to hybrid cloud and real-time enterprise event fabrics.
REST & OpenAPI 3.0 Enablement
Implement bidirectional REST endpoints directly into CICS, IMS, and IBM i programs using z/OS Connect EE and Integrated Web Services (IWS). No screen scraping, low overhead, and full OpenAPI 3.0 schema generation.
Real-Time Event Streaming
Bridge mainframe core transactions directly to enterprise event streams with Apache Kafka on z/OS, IBM MQ Advanced, and Confluent connectors, enabling sub-second ledger replication to cloud data lakes.
Db2 Schema & DDL Evolution
Modernize flat VSAM files and archaic DDS physical/logical files into true relational Db2 for z/OS and Db2 for i schemas with modern indexes, temporal tables, and high-performance stored procedures.
Mainframe DevSecOps & Git CI/CD
Retire cumbersome Changeman / Endevor silos. Migrate your teams to modern Git workflows using IBM Dependency Based Build (DBB), GitLab/GitHub Actions, and Red Hat Ansible Certified Content for IBM Z.
zCX Containerization & Linux on Z
Deploy Docker/OCI microservices directly on z/OS Container Extensions (zCX) and LinuxONE instances, co-locating modern Python, Node, and Go workloads with sub-millisecond memory-speed links to z/OS Db2.
Pervasive Encryption & Zero-Trust
Configure IBM CPACF hardware cryptographic coprocessors, CP Assist hardware acceleration, pervasive dataset encryption, and secure RACF / ACF2 role mappings across modernized API boundaries.
Custom Systems Development on Z & I
Build resilient, high-throughput transactional engines directly inside z/OS and IBM i operating environments.
CICS & IMS Transaction Architecture
System/77 designs and constructs ultra-high-throughput transactional subsystems for core banking, insurance underwriting, and payment processing.
- › Channels & Containers: Moving past 32KB COMMAREA limits into multi-megabyte structured binary and JSON payloads.
- › Threadsafe Optimization: Upgrading CICS programs to OPENAPI (L8/L9 TCBs) to eliminate Quasi-Reentrant (QR) bottleneck locks.
- › Asynchronous Transaction Processing: Implementing non-blocking sub-tasks via CICS RUN TRANSID and event queues.
Modern ILE RPG Software Architecture
We design clean, maintainable modular architectures for IBM i systems, transforming legacy monolithic RPG programs into enterprise service programs.
- › Service Programs (*SRVPGM): Encapsulated domain logic with versioned binder language export source.
- › Activation Group Management: Eliminating default activation group (*DFTACTGRP) memory leaks with named activation groups.
- › Subprocedures & Parameter Signatures: Strongly-typed signatures, CONST and VALUE parameter handling, and local scoping.
UNIX System Services & PASE Development
Modern systems engineering on the mainframe POSIX subsystem. We author native daemons, CLI utilities, and HTTP microservices running directly on USS and PASE.
- › Native Rust, C++ & Go: Compiling native binaries for s390x architecture with zero-overhead z/OS syscall interop.
- › EBCDIC / ASCII Code Page Handling: Seamless file system tagging and automatic runtime translation (AUTOCVT).
- › Cross-Platform Tooling: Daemonizing long-running batch monitors, telemetry agents, and protocol bridges.
APF Exits & Systems Programming
Deep z/OS and IBM i systems programming. Authoring high-privilege exits, security hooks, and performance monitoring routines.
- › Authorized Program Facility (APF): Writing Supervisor State (Key 0-7) authorized routines and SVC handlers.
- › SMF Telemetry Processing: Building custom SMF record generators (Types 128-255) for auditable compliance streams.
- › Security System Exits: RACF (ICHRX01), ACF2, and Top Secret pre- and post-validation custom exit programming.
Legacy Code Updates & Remediation
Mathematically verified source-to-source code transformations across the 5 core languages powering institutional computing.
COBOL Modernization & ARCH Vector Optimization
IBM has ended service for COBOL v4. Upgrading to COBOL v6 is not a simple recompile — it alters memory structures, padding, and binary truncation rules (TRUNC(STD/OPT/BIN)).
HLASM 64-Bit Conversion & Macro Optimization
Core batch and system exits written in Assembly are often untouched for 25+ years. We expand memory addressing, optimize instruction pipelines, and eliminate risk.
PL/I Enterprise Migration & Modern Data Typing
PL/I powers many of the world's most sophisticated banking and financial derivatives engines. We modernize archaic syntax into modern modular packages.
Total Free-Form RPG & Embedded SQL Transformation
Fixed-column RPG is virtually unreadable by modern software engineers. We convert legacy code to 100% free-form **FREE syntax that any modern developer can maintain.
REXX Modernization, Scripting Architecture & Tooling
REXX is the connective tissue of mainframe systems administration and batch automation. We audit, refactor, and modernize mission-critical REXX execs to prevent silent failures and ensure long-term maintainability.
TSO/E & ISPF Dialog Modernization: Refactoring monolithic ISPF dialogs, panels, and table services into clean, modular, parameter-driven execs.
DSNREXX Db2 Automation: Modernizing direct SQL execution routines, cursor management, and transactional batch scripts against Db2 for z/OS.
Python & Ansible Bridging: Migrating fragile legacy CLIST/REXX command procedures into Red Hat Ansible Certified Content for IBM Z and native Python.
Before & After Modernization Diff Showcase
Select a language below to examine real-world refactoring delivered by System/77 architects.
RPG: Fixed Column RPG III to Free-Form **FREE with Embedded SQL
FCUSTMAS IF E K DISK
D CUSTID S 9P 0
D BALDUE S 9P 2
C CUSTID CHAIN CUSTREC 50
C N50 MOVE BALDUE OUTBAL
C N50 MOVE *ON *IN30
C 50 MOVE *OFF *IN30
C RETURN**FREE
ctl-opt dftactgrp(*no) actgrp('SYS77');
dcl-proc GetCustomerBalance export;
dcl-pi *n packed(9:2);
inCustId packed(9:0) const;
end-pi;
dcl-s outBalance packed(9:2) inz(0);
exec sql
select balance_due into :outBalance
from customer_master
where customer_id = :inCustId;
if sqlcode = 0;
return outBalance;
else;
return -1;
endif;
end-proc;The System/77 4-Stage Modernization Lifecycle
Our proven engineering methodology guarantees mathematical equivalence and zero disruption to ongoing business cycles with full knowledge transfer.
01 AST Static Analysis & Mapping
Using our proprietary LSP AST parsers, we build complete call graphs, database access matrices, and dead code maps across your entire codebase.
02 Interface Decoupling
Business rules are decoupled from I/O boundaries (BMS maps, flat files). We construct strict OpenAPI 3.0 or JSON contracts for external access.
03 Semantic Equivalence Testing
Automated golden test harnesses execute historical transaction logs simultaneously through both legacy and refactored code to guarantee bit-for-bit output equivalence.
04 Phased Parallel Cutover
Canary deployments run concurrently alongside production transactions with automated rollback protection and engineer training on modern CI/CD tools.
Speak with a Mainframe & Midrange Principal Architect
Discuss your architectural goals, legacy remediation requirements, or request a scoped code audit. A senior systems architect will respond within 1 business day under NDA.