COBOL Manual for TNS/E Programs (H06.03+)

Procedure Division Verbs

HP COBOL Manual for TNS/E Programs—520347-003

9-34

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CHECKPOINT for Process Pairs

When a requester that is running as a process pair sends a message, and the

backup process takes over before the requester receives a reply, the server can

resend the reply automatically—if a CHECKPOINT statement executes after the

server reads the requester’s message but before the server writes a reply (or

generates one automatically with another READ). When this happens, the server

does not see the duplicate message. The CHECKPOINT statement can execute

even if the server is not running as a process pair.

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A Process Pair Cannot Update an SQL/MP or SQL/MX Database

An HP COBOL program that runs as a process pair cannot update an SQL/MP or

SQL/MX database.

CLOSE terminates processing of one or more open files or reels of tape. An optional

LOCK phrase prevents the program from reopening the file (unless the file is

dynamically assignable—see #DYNAMIC).

If a file is closed but not locked, the only I-O operation the process can perform on that

file is an open operation. If the file is closed and locked, the process cannot perform

any I-O operation on the file.

CLOSE has these formats:

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CLOSE for Sequential and Line Sequential Files

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CLOSE for Relative, Indexed, and Queue Files

CLOSE for Sequential and Line Sequential Files

Throughout this topic, “sequential file” means both sequential and line sequential files

unless otherwise noted.

Note. A COBOL program must not modify the contents of a checkpoint list directly. The

execution logic of the routines and the CHECKPOINT statement maintain checkpoint lists

without the need for any other program action.

file-name

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VST138.vsd