COBOL Manual for TNS and TNS/R Programs

Procedure Division Verbs
HP COBOL Manual for TNS and TNS/R Programs—522555-006
9-159
Unconditional PERFORM
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Procedure Relationships and the Ends of PERFORM Cycles
There is no necessary relationship between proc-1 and proc-2, except that a
PERFORM cycle begun at the procedure named by proc-1 ends when control
reaches the return point following the last statement of the procedure named by
proc-2. GO TO statements, PERFORM statements, CALL or ENTER statements,
and so forth, can occur in the logical sequence of statements executed during a
PERFORM cycle. If there are two or more logical points at which a cycle could
end, then proc-2 can name a paragraph consisting solely of the EXIT statement,
and all execution paths can terminate cleanly by transferring control to that
paragraph.
The existence of a return point following the end of an execution range is a
dynamic characteristic of an executing program. If control reaches the return point
defined for a PERFORM statement that is not in the process of execution (that is,
is not currently performing a cycle), then control passes through to the next
paragraph in accordance with the normal rules for implicit transfer of control from
one statement to the next.
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In-line and Out-of-Line PERFORM Statements
The PERFORM imperative-statement END-PERFORM form of the
statement is an “in-line PERFORM statement.” The PERFORM procedure-
group form of the statement is an “out-of-line PERFORM statement.”
The descriptions of the action of the PERFORM statement in this section are
expressed in terms of the out-of-line PERFORM statement. The execution of an in-
line PERFORM statement is exactly equivalent to that of an out-of-line PERFORM
statement, with the exception that the statements contained in imperative-
statement in the in-line PERFORM statement are executed in place of the
statements within the range of procedure-group. Unless specially qualified by
the term in-line or out-of-line, all the considerations that apply to the out-of-line
PERFORM statement also apply to the in-line PERFORM statement.
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Execution and Transfers of Control
Section 8, Procedure Division, explains the execution of sections and paragraphs
as well as explicit and implicit transfers of control.
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Range of the PERFORM Statement
The range of an out-of-line PERFORM statement is the statements contained
within the range of procedure-group.
The range of an in-line PERFORM statement is the statements contained within
the PERFORM statement.