Pattern-Guided Static Analysis for APIfication of COBOL Monoliths

Abstract

Legacy COBOL mainframes resist APIfication due to monolithic structure and scattered logic. We present a novel pipeline that takes code blocks selected and validated by the user, potentially with AI-assisted boundary suggestions, and generates compilable API modules with request/response copybooks. Key innovations include: (1) five COBOL patterns (P1–P5) guiding analysis selection, (2) WoCC—a pattern-based call-chain approximation avoiding recursive traversal for organized monoliths, and (3) end-to-end code synthesis handling REDEFINES aliasing and inter-program calls. Unlike prior slicing (variable sets only) or ADDI (read/write reporting), we deliver deployable APIs. On GENAPP/CBSA/industry systems, signature inference drops from weeks to minutes; refactoring effort reduces by 15–50%. Practitioners validated precision; modules deployed via z/OS Connect pass functional tests.