The intent of this document is to provide an introduction to mainframe file formats and concepts for users who are primarily familiar with PC-based systems. Mainframe data formats differ significantly from those commonly encountered on PCs — from fixed-length record structures and EBCDIC encoding to packed decimal (COMP-3) fields and hierarchical COBOL copybook definitions. Understanding these differences is essential for working effectively with mainframe data in modern distributed environments.
By familiarizing yourself with these concepts, you will be better equipped to use Cobrix — a COBOL data source for Apache Spark — to parse and process mainframe files with confidence.