COBOL main-proc

In COBOL programming, the main-procedure (also known as a program unit or module) serves as the entry point for executing a COBOL program. It typically includes logic and control structures that organize the flow of the application.

Regarding the maximum sizes in COBOL, there are two versions mentioned:
1. For COBOL I, the specific limit for a 01 level item (data items within a structure) isn't provided in your reference[^1]. You might need to consult a COBOL I specification or reference guide for this information.
2. In COBOL II, the maximum size of a 01 level item is given as 16,777,215 bytes, which corresponds to a limitation on the amount of data that can be stored in a single record or field.

The distinction between COBOL and COBOL II, as pointed out, lies primarily in their capabilities with respect to file handling and storage access. COBOL running on PCs may have limitations to flat files and accessible storage, while COBOL II on mainframe systems like VS COBOL II allows for much larger amounts of storage (up to 16MB or 2GB) and more efficient I/O operations through features like VSAM.