https://www.youngju.dev/blog 천천히 올바르게. AI Researcher & DevOps Engineer Youngju's tech blog. GPU/CUDA, LLM, MLOps, Kubernetes AI workloads, distributed training, and data engineering. ko fjvbn2003@gmail.com (Youngju Kim) fjvbn2003@gmail.com (Youngju Kim) Sat, 16 May 2026 00:00:00 GMT https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive.en https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive.en The giant that was supposed to die is still alive. In 2026, the transaction backbone of every major bank, insurer, government, and manufacturer still runs on IBM Z and IBM i. The z17 launched in September 2025 with the Telum II processor and on-chip AI, while 200B+ lines of COBOL meet watsonx Code Assistant for Z, GitHub Copilot, and AWS Mainframe Modernization for yet another modernization cycle. This guide covers IBM z17 and z16, IBM i (formerly AS/400), RPG, JCL, CICS, DB2 z/OS, IMS, PL/I, the non-IBM mainframes (Fujitsu BS2000, NEC ACOS, Unisys ClearPath), modernization patterns like Strangler Fig and Anti-corruption Layer, the state of Korean and Japanese financial mainframes, and who exactly should be learning COBOL in 2026. Sat, 16 May 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) mainframeibm-zibm-z17ibm-z16ibm-ias400cobolrpgjclcicsdb2-zosimspl-ifujitsu-bs2000nec-acosunisys-clearpathaws-mainframe-modernizationmicro-focusvisual-cobolopentextwatsonx-code-assistantgithub-copilot-cobolzcxlinux-on-zlinuxoneherculesgnucobolstrangler-fig2026deep-diveenglish https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive.ja https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive.ja 死んだはずの巨人はまだ生きている。2026年も世界中の銀行・保険・行政・製造のトランザクション基盤は依然として IBM Z と IBM i の上で動く。2025年9月発表の z17 は Telum II プロセッサにオンチップ AI を搭載し、2,000億行を超える COBOL は watsonx Code Assistant for Z、GitHub Copilot、AWS Mainframe Modernization に出会って再び現代化サイクルへ。Fujitsu BS2000、NEC ACOS、Unisys ClearPath ら非 IBM メインフレームの現在、RPG・JCL・CICS・Db2 z/OS・IMS・PL/I の位置づけ、Strangler Fig や Anti-corruption Layer といったパターン、日韓金融機関のメインフレーム運用、そして 2026 年に COBOL を学ぶべき人は誰か — レガシー基盤の全てを一気通貫で。 Sat, 16 May 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) mainframeibm-zibm-z17ibm-z16ibm-ias400cobolrpgjclcicsdb2-zosimspl-ifujitsu-bs2000nec-acosunisys-clearpathaws-mainframe-modernizationmicro-focusvisual-cobolopentextwatsonx-code-assistantgithub-copilot-cobolzcxlinux-on-zlinuxoneherculesgnucobolstrangler-fig2026deep-dive日本語 https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive https://www.youngju.dev/blog/culture/2026-05-16-mainframe-cobol-legacy-systems-2026-ibm-z17-ibm-i-as400-cobol-rpg-watsonx-code-assistant-z-deep-dive 죽었다고 했던 거인은 여전히 살아있다. 2026년에도 전 세계 은행·보험·정부·제조의 트랜잭션 백본은 여전히 IBM Z와 IBM i 위에서 돈다. 2025년 9월 출시된 z17은 Telum II 프로세서에 칩-온-칩 AI 가속을 박아 넣었고, 200B 라인이 넘는 COBOL은 watsonx Code Assistant for Z와 GitHub Copilot, AWS Mainframe Modernization을 만나 다시 한 번 현대화의 사이클로 들어간다. Fujitsu BS2000, NEC ACOS, Unisys ClearPath까지 비-IBM 메인프레임의 현재, RPG·JCL·CICS·DB2 z/OS·IMS·PL/I의 위치, Strangler Fig·Anti-corruption layer 같은 패턴, 한국·일본 금융권의 메인프레임 운영 현황, 그리고 누가 지금 COBOL을 배워야 하는지까지 — 2026년 레거시 백본의 모든 것을 한 번에. Sat, 16 May 2026 00:00:00 GMT fjvbn2003@gmail.com (Youngju Kim) mainframeibm-zibm-z17ibm-z16ibm-ias400cobolrpgjclcicsdb2-zosimspl-ifujitsu-bs2000nec-acosunisys-clearpathaws-mainframe-modernizationmicro-focusvisual-cobolopentextwatsonx-code-assistantgithub-copilot-cobolzcxlinux-on-zlinuxoneherculesgnucobolstrangler-fig2026deep-dive