Identifying Procedural Structure in Cobol Programs

The principal control-flow abstraction mechanism in the Cobol language is the PERFORM statement. Normally, PERFORM statements are used in a straightforward manner to define parameterless procedures (where global variables are used to pass data into and out of procedure bodies). However, unlike most procedural constructs, distinct PERFORMed procedures can share code in arbitrarily complicated ways. In addition, PERFORMs can also be used in such a way as to causetransfers of control that do not correspondto normal call/return semantics. In this paper, we show how a Cobol program can be efficiently transformed into a semantically-equivalent procedurally well-structured representation, in which conventional procedures (i.e., with the usual call and return semantics and without code sharing) and procedure call statements replace PERFORMed code and PERFORM statements. This transformation process properly accounts for the non-procedural control flow that can result from ill-behaved PERFO...

• Type: Conference
• Year: 1999
• Where: PASTE
• Authors: John Field, G. Ramalingam
• Keywords: COBOL, Cobol Program, PASTE 1999, Perform Statements, Software Engineering