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General Formats (Continued) [ Micro Focus COBOL Language Reference ] MPE/iX 5.0 Documentation

Micro Focus COBOL Language Reference

General Formats (Continued)

The CANCEL Statement

Function.

The CANCEL statement ensures that the next time the referenced program is
called it will be in its initial state.

General Format.

Syntax Rules.

1. Literal-1 must be a nonnumeric literal.

2. Identifier-1 must reference an alphanumeric data item.

General Rules.

1. Literal-1 or the content of the data item referenced by
identifier-1 identifies the program to be canceled. The name must
contain the program-name contained in the PROGRAM-ID paragraph of
the program to be canceled (see The Program_ID Parargraph earlier
in this chapter, particularly in regard to case sensitivity).
Alternatively, the name may identify a file that contains
executable program code for the program to be canceled. The
results of psecifying different names that identify the same file
in a CANCEL statement are operating system specific. See your
COBOL System Reference for details of how your system matches the
given name ot previously called programs held in library files.

If the name conatins the entry-name contained in an ENTRY
statement, the results are undefined.

2. Subsequent to the execution of an explicit or implicit CANCEL
statement, the program referred to therein ceases to have any
logical relationship to the run unit in which the CANCEL statement
appears. If the program referenced by a successfully executed
explicit or implicit CANCEL statement in a run unit is
subsequently called in that run unit, that program is in its
initial state. See the section Initial State Of A Program earlier
in this chapter.

3. A program named in a CANCEL statement in another program must be
callable by that other program. See the sections Scope Of Names
and The CALL Statement, earlier in this chapter.

4. For ANS85 only: When an explicit or implicit CANCEL statement is
executed, all programs contained in the program referenced by the
CANCEL statement are also cancelled. The result is the same as if
a valid CANCEL statement were executed for each contained program
in the reverse order in which the programs appear in the separate
program .

5. A program named in the CANCEL statement must not refer directly or
indirectly to any program that has been called and has not yet
executed an EXIT PROGRAM or GOBACK (OSVS, VSC2 and MF only)
statement.

6. A logical relationship to a cancelled program is established only
by execution of a subsequent CALL statement naming that program.

7. A called program is cancelled either by being referred to as the
operand of a CANCEL statement, by the termination of the run unit
of which the program is a member, or by execution of an EXIT
PROGRAM statement in a called program that possesses the initial
attribute (ANS85 only).

8. No action is taken when an explicit or implicit CANCEL statement
is executed naming a program that has not been called in this run
unit has been called and is at present cancelled or is a non-COBOL
program. Control is transferred to the next executable statement
following the CANCEL statement.

9. For ANS85 only: The contents of data items in external data
records described by a program are not changed when that program
is cancelled .

10. During execution of an explicit or implicit CANCEL statement, an
implicit CLOSE statement without any optional phrases is executed
for each file in the open mode that is associated with an internal
file connector in the program named in the CANCEL statement. Any
USE procedures associated with any of these files are not executed
(ANS85).

11. The CANCEL statement determines whether or not a subprogram will
be re-entered in initial or last-used state. It does not
necessarily free any memory used by the subprogram. However, in
many operating systems, if the subprogram has been dynamically
loaded, this statement will also free the memory originally used
by the subprogram. EXTERNAL files and data areas of the
subprogram are never freed by a CANCEL statement.

For MF only: The CHAIN Statement

Function.

The CHAIN statement transfers control from one object program to another
in the run unit with no subsequent return of control. The effect is as
though the chained program is the main program in the new run unit.

General Format.

Syntax Rules.

1. The syntax of the CHAIN statement is similar to the syntax of the
CALL statement and the two are subject to common syntax rules as
indicated in the section The CALL Statement. All the identifiers,
literals and integers in the general format of the CHAIN statement
correspond to the identifiers, literals and integers of the CALL
statement.

General Rules.

1. Literal-1 or the content of the data item referenced by
identifier-1 is the name of the chained program. The program in
which the CHAIN statement appears is the chaining program.

The chained program must be a COBOL program that is not a nested
program. The name of the chained program must contain the name
contained in the PROGRAM-ID paragraph of the chained program (see
The Program-ID Paragraph earlier in this chapter particularly in
regard to case sensitivity). Alternatively, the name of the
chained program may contain a name which identifies a file that
contains executable program code for the chained program. See
your COBOL System Reference for details of how your system matches
the given name to previously chained programs, program filenames
or programs held in library files.

2. If, when a CHAIN statement is executed, the program specified by
the CHAIN statement is made available for execution, control is
transferred to the chained program, and the chaining program,
together with any COBOL programs called by the chaining program,
are canceled. The chained program is not under the control of a
chaining program and so any EXIT PROGRAM executed within the
chained program has no effect.

3. If, when a CHAIN statement is executed, the program specified by
the CHAIN statement is not made available for execution, thena
fatal run time error is given.

4. Chained programs can contain CHAIN statements. A CHAIN statement
within a chained program may reference any program except itself.

5. The form of the CHAIN statement is similar to the form of the CALL
statement and the two are subject to common general rules as
indicated in the section The CALL Statement. All the identifiers,
literals and integers in the general format of the CHAIN statement
correspond to the identifiers, literals and integers of the CALL
statement. Also, where the expressions calling program and called
program are used, these can be considered equivalent to the
expressions chaining program and chained program.

6. The chain operation moves the value from each data item referenced
in the USING phrase of the CHAIN statement to the data item
referenced by the corresponding data-name in the USING phrase of
the PROCEDURE DIVISION header of the chained program.

7. The value of any data item with USAGE POINTER or USAGE
PROCEDURE-POINTER that is passed as an operand in the USING phrase
must not represent the address that was originally derived from a
COBOL data item.

8. The END-CHAIN phrase delimits the scope of the CHAIN statement.

9. The USING phrase must not be used if you have specified the system
directive INTLEVEL"1".

The CLOSE Statement

Function.

The CLOSE statement terminates the processing of reels/units and files,
with optional rewind and/or lock or removal where applicable.

General Formats.

Format 1 (Record Sequential Files).

Format 2 (Line Sequential - MF only), (Relative and Indexed Files - ANS85
only).

Syntax Rules.

All Formats (All Files).

1. The files referenced in the CLOSE statement need not all have the
same organization or access.

Format 1 (Record Sequential Files).

2. For MF only: The REEL and UNIT phrases should be specified
only for files which have had MULTIPLE REEL or MULTIPLE UNIT
specified in their SELECT clause. If your run-time system does
not recognize multi-unit files, the statements CLOSE REEL and
CLOSE UNIT are "null" statements; that is, they are documentary
only. It is important that no other files are open on the
device(s) closed by a CLOSE REEL or CLOSE UNIT statement.

For OSVS only: The statements CLOSE REEL WITH LOCK and CLOSE
UNIT WITH LOCK are treated as equivalent to CLOSE REEL FOR
REMOVAL.

3. For OSVS only: The DISP option is applicable only to tape files.

For MF only: It is documentary only.

General Rules.

All Formats (All Files).

1. A CLOSE statement can be executed only for a file in an open mode.

2. Following the successful execution of a CLOSE statement the record
area associated with file-name-1 is no longer available. The
unsuccessful execution of such a CLOSE statement leaves the
availability of the record area undefined.

3. For ANS85 only: If a file is in the open mode when a STOP RUN
statement is executed the file will be closed. If a file has been
opened in a called program and not closed in that program prior to
the execution of a CANCEL statement for the program that file will
be closed .

4. For MF only: Following the successful execution of a CLOSE
statement, all record or file locks held by the run unit on the
closed file are released.

5. The execution of the CLOSE statement causes the value of the I/O
status associated with file-name-1 to be updated. (See the
section I/O Status earlier in this chapter.)

6. The results of executing each type of CLOSE statement for each
category of file are summarized in Table 4-12.

Table 4-12 : Relationship of Categories of Files and the Formats of the CLOSE Statement

----------------------------------------------------------------
| | |
| CLOSE | File Category |
| Statement | |
| Format | |
| | |
----------------------------------------------------------------
| | | | | |
| | Non-Reel/ | Record | Record | Non- |
| | Unit | Sequential| Sequential| record |
| | | Single- | Multi- | Sequential|
| | | Reel/ | Reel/ | Single/ |
| | | Unit | Unit | Multi- |
| | | | | Reel/ |
| | | | | Unit |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE | C | C, G | A, C, G | C |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE WITH | C, E | C, E, G | A, C, E, | C, E |
| LOCK | | | G | |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE WITH | C*, H* | B, C | A, B, C | X |
| NO REWIND | | | | |
| record | | | | |
| sequential | | | | |
| only | | | | |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE | F* | F*, G* | F, G | X |
| REEL/UNIT | | | | |
| record | | | | |
| sequential | | | | |
| only | | | | |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE | F* | D*, F*, | D, F , G | X |
| REEL/UNIT | | G* | | |
| FOR REMOVAL | | | | |
| record | | | | |
| sequential | | | | |
| only | | | | |
| | | | | |
----------------------------------------------------------------
| | | | | |
| CLOSE | X | X | F, B | X |
| REEL/UNIT | | | | |
| WITH NO | | | | |
| REWIND | | | | |
| record | | | | |
| sequential | | | | |
| only | | | | |
| | | | | |
----------------------------------------------------------------

* ANS85

The definitions of the symbols in the table are given below. Where the
definition depends on whether the file is an input, output or input-
output file, alternate definitions are given; otherwise, a definition
applies to input, output, and input-output files.

A. Previous Reels/Units Unaffected

Input Files and Input-Output Files:

All reels/units in the file prior to the current reel/unit are
processed except those reels/units controlled by a prior CLOSE
REEL/UNIT statement. If the current reel/unit is not the last
in the file, the reels/units in the file following the current
one are not processed.

Output Files:

All reels/units in the file prior to the current reel/unit are
processed except those reels/units controlled by a prior CLOSE
REEL/UNIT statement.

B. No Rewind of Current Reel

The current reel/unit is left in its current position.

C. Close File

Input Files and Input-Output Files (Sequential Access Mode):

If the file is at the end and label records are specified for
the file, the labels are processed according to the operating
system label convention. The behavior of the CLOSE statement
when label records are specified but not present, or when label
records are not specified but are present, is undefined. If the
file is at the end and label records are not specified for the
file, label processing does not take place, but other closing
operations dependent on the run-time system are executed. (See
your COBOL System Reference.) If the file is not at the end,
the closing operations dependent on the RTS are executed, but
there is no ending label processing.

Input Files and Input-output Files (Random or Dynamic Access
Mode); Output Files (Random, Dynamic or Sequential Access Mode):

If label records are specified for the file, the labels are
processed according to the operating system standard label
convention. The behavior of the CLOSE statement when label
records are specified but not present, or when label records are
not specified but are present, is undefined. If label records
are not specified for the file, label processing does not take
place, but other closing operations dependent on the run-time
system are executed.

D. Reel/Unit Removal

The reel or unit can be accessed again, in the proper order of
reels or units in the file, if a CLOSE statement without the
REEL or UNIT phrase has previously been executed for this file
followed by the execution of an OPEN statement for the file.

E. File Lock

This file cannot be opened again during this execution of this
run unit.

F. Close Reel/Unit

Input Files and Input-Output Files (Reel/Unit Media):

1. For ANS85 only: If the current reel/unit is the last or
only reel/unit for the file, no reel/unit swap takes
place; the current volume pointer remains unchanged, and
the file position indicator is set to indicate that no
next reel/unit exists .

2. If another reel/unit exists for the file, a reel/unit
swap occurs, the current volume pointer is updated to
point to the next reel/unit existing in the file, the
standard beginning reel/unit label procedure is executed,
and the file position indicator is set to one less than
the number of the first record existing on the new
current volume. If no data records exist for the current
volume, another reel/unit swap occurs.

Output Files (Reel/Unit Media):

The following operations take place;

1. Execution of the standard ending reel/unit label
procedure.

2. A reel/unit swap.

3. Execution of the standard beginning reel/unit label
procedure.

4. The next executed WRITE statement that references that
file directs the next logical data record to the next
reel/unit of the file.

For ANS85 only: Input Files, Input-Output Files, and Output
Files (Non-Reel/Unit Media): Execution of this statement is
considered successful. The file remains in the open mode, the
file position indicator remains unchanged, and no action takes
place except as specified in General Rule 4.

G. Rewind

The current reel or analogous device is positioned at its
physical beginning.

H. For ANS85 only: Optional Phrases Ignored (ANS85)

The CLOSE statement is executed as if none of the optional
phrases is present.

X. Illegal

This is an illegal combination of a CLOSE option and a file
category. The results at object time are undefined.

Format 1 (Record Sequential Files).

Except where otherwise stated in the general rules below, the terms
"reel" and "unit" are equivalent and completely interchangeable in the
CLOSE statement. Treatment of sequential mass storage files is logically
equivalent to the treatment of a file on tape or analogous sequential
media.

1. In order to show the effect of various types of CLOSE statements
as applied to various storage media, all files are divided into
the following categories:

a. Non-reel/unit. A file whose input or output medium is such
that the concepts of rewind and reels/units have no
meaning.

b. Sequential single-reel/unit. A sequential file that is
entirely contained on one reel/unit.

c. Sequential multi-reel/unit. A sequential file that is
contained on more than one reel/unit.

2. If the OPTIONAL phrase has been specified for the file in the
FILE-CONTROL paragraph of the Environment Division and the file is
not present, the standard end-of-file processing is not performed
for that file.

3. If a CLOSE statement without the REEL or UNIT phrase has been
executed for a file, no other statement (except the SORT or MERGE
statements with the USING or GIVING phrases) can be executed that
references that file, either explicitly or implicitly, unless an
intervening OPEN statement for that file is executed.

4. The WITH NO REWIND and FOR REMOVAL phrases will have no effect at
object time if they do not apply to the storage media on which the
file resides.

5. If WITH LOCK is specified, the file cannot be reopened during the
current execution of the run unit. Otherwise a normal CLOSE takes
effect.

For MF only: This option has no connection with the record or
file locking used when sharing files.

All Formats (All Files).

6. If a CLOSE statement has been executed for a file, no statement
other than a delete file (MF only) can be executed that
references that file, either explicitly or implicitly, unless an
intervening OPEN statement for that file is executed.

7. If WITH LOCK is specified, the file cannot be reopened during the
current execution of the run unit.

For MF only: The COMMIT Statement

Function.

The COMMIT statement releases all record locks in all files held by this
run unit. For COBOL systems that support the WITH...ROLLBACK clause of
the SELECT statement as other than documentary, COMMIT indicates the end
of the current transaction and makes the effects of that transaction
permanent.

General Format.

General Rules.

1. Execution of the COMMIT statement causes all record locks in all
files held by the run unit to be released.

2. The file lock on an exclusive file is not affected by the COMMIT
statement.

3. If your COBOL system supports the WITH...ROLLBACK clause of the
SELECT statement as other than documentary, then the COMMIT verb:

a. Indicates completion of the current transaction

b. Makes all changes applied during the transaction permanent.

The COMPUTE Statement

Function.

The COMPUTE statement assigns to one or more data items the value of an
arithmetic expression.

General Format.

Syntax Rules.

1. For OSVS, VSC2, and MF only: Identifiers that appear only to the
left of "=" must refer to either an elementary numeric item or an
elementary numeric edited item or (a floating-point item).

2. For OSVS, VSC2 and MF only: "Equal" and "=" are synonymous.

General Rules.

1. See the sections The ROUNDED Phrase, The ON SIZE ERROR Phrase,
Arithmetic Statements, Overlapping Operandsand Multiple Results In
Arithmetic Statements in this chapter; and the sections Explicit
And Implicit Scope Terminators in the chapter Concepts of the
COBOL Language and Delimited Scope Statements in the chapter
Concepts of a COBOL Program.

2. An arithmetic expression consisting of a single identifier or
literal provides a method of setting the values of identifier-1
equal to the value of the single identifier or literal.

3. The COMPUTE statement allows the user to combine arithmetic
operations without the need to explicitly store intermediate
results in temporary data items, as would be necessary using the
arithmetic statements ADD, SUBTRACT, MULTIPLY and DIVIDE. The
expression is evaluated to as many digits as possible, and
truncated or rounded to fit into identifier-1.

For OSVS and VSC2 only: The intermediate results obtained during
the expression evaluation are truncated as if they were moved to
data items whose PICTURE is determined by the COBOL system. This
behavior is selected using the ARITHMETIC directive. See your
COBOL System Reference for details.

4. If more than one identifier is specified for the result of the
operation, that is preceding "=", the value of the arithmetic
expression is computed, and then this value is stored as the new
value of each occurrence of identifier-1 in turn.

MPE/iX 5.0 Documentation