I see two problems with such a claim. First, a practical one: COBOL programs can call external functions[0]. Second, a theoretical one: Even if a given program

I see two problems with such a claim. First, a practical one: COBOL programs can call external functions[0]. Second, a theoretical one: Even if a given program does not call external functions, they often read data written by other programs and write data read by other programs. The security implications seem obvious; a bug in a COBOL program can cause undesirable consequences outside of the program. [0]: https://www.ibm.com/docs/en/zos/2.1.0?topic=cbcc-calling-between-c-cobol https://www.ibm.com/docs/en/zos/2.1.0?topic=cbcc-calling-bet...