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General Formats (Cont.) The RELEASE Statement Function. The RELEASE statement transfers records to the initial phase of a SORT operation. General Format.Syntax Rules. 1. A RELEASE statement can only be used within the range of an input procedure associated with a SORT statement for a file whose sort-merge file description entry contains record-name. (See the section The SORT Statement in this chapter.) 2. Record-name must be the name of a logical record in the associated sort-merge file description entry and can be qualified. 3. For ANS85 only: If identifier is a function-identifier, it must reference an alpha- numeric function. When identifier is not a function-identifier, record-name and identifier must not reference the same storage area. 4. For MF, OSVS and VSC2 only: Record-name can be defined as a floating-point item. 5. For MF, OSVS and VSC2 only: Identifier can be a floating-point item. General Rules. 1. The execution of a RELEASE statement causes the record named by record-name to be released to the initial phase of a sort operation. 2. If the FROM phrase is used, the contents of the identifier data area are moved to record-name, then the contents of record-name are released to the sort file. Moving records takes place according to the rules specified for the MOVE statement without the CORRESPONDING phrase. The information in the record area is no longer available, but the information in the data area associated with identifier is available. 3. After the execution of the RELEASE statement, the logical record is no longer available in the record area unless the associated sort-merge file is named in a SAME RECORD AREA clause. The logical record is also available to the program as a record of other files referenced in the same SAME RECORD AREA clause as the associated sort-merge file, as well as to the file associated with record-name. When control passes from the input procedure, the file consists of all those records which were placed in it by the execution of RELEASE statements. The RETURN Statement Function. The RETURN statement obtains either sorted records from the final phase of a SORT operation or merged records during a MERGE operation. General Format.Syntax Rules. 1. File-name must be described by a sort-merge file description entry in the Data Division. 2. A RETURN statement can only be used within the range of an output procedure associated with a SORT or MERGE statement for file-name. 3. The INTO phrase must not be used when the input file contains logical records of various sizes as indicated by their record descriptions. The storage area associated with identifier and the record area associated with file-name must not be the same storage area. 4. For MF, OSVS and VSC2 only: Identifier-1 can be a floating-point item. General Rules. 1. When the logical records of a file are described with more than one record description, these records automatically share the same storage area; this is equivalent to an implicit redefinition of the area. The contents of any data items which lie beyond the range of the current data record are undefined at the completion of the execution of the RETURN statement. 2. The execution of the RETURN statement causes the next existing record in the file referenced by file-name, as determined by the keys listed in the SORT or MERGE statement, to be made available in the record area associated with file-name. If no next logical record exists in the file referenced by file-name, the at end condition exists and control is transferred to imperative-statement-1 of the AT END phrase. Execution continues according to the rules for each statement specified in imperative-statement-1. If a procedure branching or conditional statement which causes explicit transfer of control is executed, control is transferred according to the rules for that statement. Otherwise, upon completion of the execution of imperative-statement-1, control is transferred to the end of the RETURN statement and the NOT AT END phrase if specified is ignored (ANS85 only). When the at end condition occurs, execution of the RETURN statement is unsuccessful and the contents of the record area associated with file-name are undefined. After the execution of imperative-statement-1 in the AT END phrase, no RETURN statement can be executed as part of the current output procedure. 3. For ANS85 only: If an at end condition does not occur during the execution of a RETURN statement, then after the record is made available and after executing any implicit move resulting from the presence of an INTO phrase, control is transferred to imperative-statement-2, if specified. Otherwise, control is transferred to the end of the RETURN statement. 4. For ANS85 only: The END-RETURN phrase delimits the scope of the RETURN statement. 5. The INTO phrase can be specified in a RETURN statement: a. If only one record description is subordinate to the sort-merge file description entry, or: b. If all record-names associated with file-name and the data item referenced by identifier describe a group item or an elementary alphanumeric-item. 6. The result of the execution of a RETURN statement with the INTO phrase is equivalent to the application of the following rules in the order specified: a. The execution of the same RETURN statement without the INTO phrase. b. The current record is moved from the record area to the area specified by identifier according to the rules for the MOVE statement without the CORRESPONDING phrase. The size of the current record is determined by rules specified for the RECORD clause. If the file description entry contains a RECORD IS VARYING clause, the implied move is a group move. The implied MOVE statement was unsuccessful. Any subscripting associated with identifier-1 is evaluated after the record has been read and immediately before it is moved to the data item. The record is available in both the record area and the data item referenced by identifier-1. The REWRITE Statement Function. The REWRITE statement logically replaces a record existing in a disk file. General Formats. Format 1 (Line Sequential Files) (MF).Format 2 (Record Sequential Files).Format 3 (Relative and Indexed Files).Directives and Run-time Switches. 1. In addition to flagging and reserved words directives, the following directives may impact either the syntax or semantics described in this section. See your COBOL System Reference for details. * WRITE-LOCK - acquires a record lock for a REWRITE statement when multiple recording locking is used. 2. The following run-time switches may impact the semantics described in this section. See your COBOL System Reference for details. * N - controls the insertion of null characters before control characters when writing line sequential records. * T - controls the insertion of tab characters when writing line sequential records. Syntax Rules. All Formats (All Files). 1. For ANS85 only: If identifier is a function-identifier, it must reference an alpha-numeric function. When identifier is not a function-identifier, record-name and identifier must not reference the same storage area. 2. Record-name is the name of a logical record in the File Section of the Data Division and can be qualified. 3. For OSVS, VSC2 and MF only: Record-name can define a floating point or DBCS item. 4. For OSVS, VSC2 and MF only: Identifier can be a USAGE DISPLAY-1 (DBCS) item or a floating- point item. Format 3 (Relative And Indexed Files). 5. The INVALID KEY phrase must not be specified for a REWRITE statement which references a file in sequential access mode. For OSVS, VSC2 only: However, it can be specified for an indexed file in sequential access mode. 6. The INVALID KEY phrase must be specified in the REWRITE statement for files in the random or dynamic access mode for which an appropriate USE procedure is not specified. General Rules. All Formats (All Files). 1. The file associated with record-name must be a disk file and must be open in the I/O mode at the time of execution of this statement. (See the section The OPEN Statement earlier in this chapter.) 2. For files in the sequential access mode the last input-output statement executed for the associated file prior to the execution of the REWRITE statement must have been a successfully executed READ statement. The operating system logically replaces the record that was accessed by the READ statement. 3. The execution of a REWRITE statement with the FROM phrase is equivalent to the execution of: MOVE identifier TO record-name followed by the execution of the same REWRITE statement without the FROM phrase. The contents of the record area prior to the execution of the implicit MOVE statement have no effect on the execution of the REWRITE statement. 4. The file position indicator is not affected by the execution of a REWRITE statement. 5. The execution of the REWRITE statement causes the value of the FILE STATUS data item, if any, associated with the file to be updated. (See the section I/O Status earlier in this chapter.) 6. For ANS85 only: The END-REWRITE phrase delimits the scope of the REWRITE statement. 7. For MF only: A REWRITE will not be successful if any other run unit holds a lock on the record to be rewritten. Formats 1 and 2 (Sequential Files). 8. The number of character positions in the record referenced by record-name must be equal to the number of character positions in the record being replaced. 9. The logical record released by a successful execution of the REWRITE statement is no longer available in the record area unless the associated file is named in a SAME RECORD AREA clause. In this case, the record is still available to the program in the record area, not only as a record of this file, but also as a record of other files named in the SAME RECORD AREA clause. For MF only: Format 1 (Line Sequential Files). 10. The REWRITE statement can be used and is considered successful whenever the record being written (after compacting by removing trailing spaces, tab compression and null insertion) is less than or equal to the length of the original compacted record. When a record is read, nulls and tab characters in the record can be expanded and this makes the record longer. Format 3 (Relative And Indexed Files). 11. The logical record released by a successful execution of the REWRITE statement is no longer available in the record area unless the associated file is saved in a SAME RECORD AREA clause, in which case the logical record is available both to the program as a record of other files appearing in the same SAME RECORD AREA clause as the associated I/O file, as well as to the file associated with record-name. Format 3 (Relative Files). 12. For a file accessed in either random or dynamic access mode, the operating system logically replaces the record specified by the contents of the RELATIVE KEY data item associated with the file. If the file does not contain the record specified by the key, the INVALID KEY condition exists. (See the section The INVALID KEY Condition in this chapter.) The updating operation does not take place and the data in the record area is unaffected. Format 3 (Indexed Files). 13. For a file in sequential access mode, the record to be replaced is specified by the value contained in the prime record key. When the REWRITE statement is executed, the value contained in the prime record data item of the record to be replaced must be equal to the value of the prime record key of the last record read from this file. 14. For a file in random or dynamic access mode, the record to be replaced is specified by the prime record key data item. 15. The contents of alternate record key data items of the record being rewritten can differ from those in the record being replaced. The operating system uses the contents of the record key data items during execution of the REWRITE statement so that the record can subsequently be accessed via any of those specified record keys. 16. The INVALID KEY condition exists when: a. Access mode is sequential and the value contained in the prime record key data item of the record to be replaced is not equal to the value of the prime record key of the last record read from this file, or: b. The value contained in the prime record key data item does not equal that of any record stored in the file, or: c. The value contained in an alternate record key data item for which a DUPLICATES clause has not been specified is equal to that of a record already stored in the file. The updating operation will not take place and the data in the record area will be unaffected. (See the section The INVALID KEY Condition in this chapter.) The ROLLBACK Statement Function. The ROLLBACK 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, the ROLLBACK statement indicates the end of the current transaction and the effects of that transaction are cancelled. General Format.General Rules. 1. Execution of the ROLLBACK 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 ROLLBACK statement. 3. If your COBOL system supports the WITH ROLLBACK clause of the SELECT statement as other than documentary, then the ROLLBACK verb: a. Indicates completion of the current transaction b. Ensures all changes applied during the transaction are cancelled. The SEARCH Statement Function. The SEARCH statement is used to search a table for a table element that satisfies the specified condition and to adjust the associated index-name to indicate that table element. General Format. Format 1.Format 2.Note that the required relational character "=" is not underlined to avoid confusion with other symbols. Syntax Rules. All Formats (All Files). 1. Identifier-1 must not be subscripted or indexed, but its description must contain an OCCURS clause and an INDEXED BY clause. The description of identifier-1 in Format 2 must also contain the KEY IS phrase in its OCCURS clause. 2. Identifier-2, when specified, must be described as USAGE IS INDEX or as a numeric elementary item without any positions to the right of the assumed decimal point. 3. For ANS85 only: If the END-SEARCH phrase is specified, the NEXT SENTENCE phrase must not be specified. For VSC2 and MF only: END-SEARCH can be specified with NEXT SENTENCE. If the NEXT SENTENCE phrase is executed, control will not pass to the next statement following the END-SEARCH, but instead will pass to the statement after the closest following period. 4. For MF only: Both imperative-statement-1 and imperative-statement-2 can be replaced by a conditional statement. Format 1. 5. Condition-1, condition-2, and so on, can be any condition as described in the section Conditional Expressions earlier in this chapter. 6. For OSVS, VSC2 and MF only: Identifier-1, the table element being searched, can be an internal or external floating-point item. Format 2. 7. All referenced condition-names must be defined as having only a single value. The data-name associated with a condition-name must appear in the KEY clause of identifier-1. Each data-name-1, data-name-2 can be qualified. Each data-name-1, data-name-2 must be indexed by the first index-name associated with identifier-1 along with other indices or literals as required, and must be referenced in the KEY clause of identifier-1. Identifier-3, identifier-4, or identifiers specified in arithmetic-expression-1, arithmetic-expression-2 must not be referenced in the KEY clause of identifier-1 or be indexed by the first index-name associated with identifier-1. When a data-name in the KEY clause of identifier-1 is referenced, or when a condition-name associated with a data-name in the KEY clause of identifier-1 is referenced, all preceding data-names in the KEY clause of identifier-1 or their associated condition-names must also be referenced. 8. For OSVS, VSC2 and MF only: Identifier-1, the table element being searched, can not be a floating-point item. 9. For OSVS, VSC2 and MF only: Neither data-name-1 nor data-name-2, the key data items, can be floating point items. However, identifier-3, identifier-4, literal-1, or literal-2, the items against which the key is compared, can be floating-point items. General Rules. All Formats. 1. The scope of a SEARCH statement can be terminated by any of the following: a. For ANS85 only: An END-SEARCH phrase at the same level of nesting. b. A separator period. c. An ELSE or END-IF (ANS85 only) associated with a previous IF statement. 2. After execution of imperative-statement-1, or imperative- statement-2 that does not terminate with a GO TO statement, control passes to the next executable sentence. 3. If identifier-1 is a data item subordinate to a data item that contains an OCCURS clause (providing for a two or three dimensional table), an index-name must be associated with each dimension of the table through the INDEXED BY phrase of the OCCURS clause. Only the setting of the index-name associated with identifier-1 (and the data item identifier-2 or index-name-1, if present) is modified by the execution of the SEARCH statement. To search an entire two or three dimensional table it is necessary to execute a SEARCH statement several times. Prior to each execution of a SEARCH statement, SET statements must be executed whenever index-names must be adjusted to appropriate settings. Format 1. 4. If Format 1 of the SEARCH is used, a serial type of search operation takes place, starting with the current index setting. a. If, at the start of execution of the SEARCH statement, the index-name associated with identifier-1 contains a value that corresponds to an occurrence number that is greater than the highest permissible occurrence number for identifier-1, the SEARCH is terminated immediately. The number of occurrences of identifier-1, the last of which is the highest permissible, is discussed in the OCCURS clause. (See the section The OCCURS Clause earlier in this chapter.) Then, if the AT END phrase is specified, imperative- statement-1 is executed; if the AT END phrase is not specified, control passes to the next executable sentence. b. If, at the start of execution of the SEARCH statement, the index-name associated with identifier-1 contains a value that corresponds to an occurrence number that is not greater than the highest permissible occurrence number for identifier-1 (the number of occurrences of identifier-1, the last of which is the highest permissible is discussed in the OCCURS clause), the SEARCH statement operates by evaluating the conditions in the order that they are written, making use of the index settings, wherever specified, to determine the occurrence of those items to be tested. If none of the conditions is satisfied, the index name for identifier-1 is incremented to obtain reference to the next occurrence. The process is then repeated using the new index-name settings unless the new value of the index-name settings for identifier-1 corresponds to a table element outside the permissible range of occurrence values, in which case the search terminates as indicated in General Rule 1a above. If one of the conditions is satisfied upon its evaluation, the search terminates immediately and the imperative statement associated with that condition is executed; the index-name remains set at the occurrence which caused the condition to be satisfied. 5. If the VARYING phrase is not used, the index- name that is used for the search operation is the first (or only) index-name that appears in the INDEXED BY phrase of identifier-1. Any other index-names for identifier-1 remain unchanged. 6. If the VARYING index-name-1 phrase is specified, and if index-name-1 appears in the INDEXED BY phrase of identifier-1, that index-name is used for this search. If this is not the case, or if the VARYING identifier-2 phrase is specified, the first (or only) index-name given in the INDEXED BY phrase of identifier-1 is used for the search. In addition, the following operations will occur: a. If the VARYING index-name-1 phrase is used, and if index-name-1 appears in the INDEXED BY phrase of another table entry, the occurrence number represented by index-name-1 is incremented by the same amount as, and at the same time as, the index-name associated with identifier-1 is incremented. b. If the VARYING identifier-2 phrase is specified, and identifier-2 is an index data item, then the data item referenced by identifier-2 is incremented by the same amount as, and at the same time as, the index associated with identifier-1 is incremented. If identifier-2 is not an index data item, the data item referenced by identifier-2 is incremented by the value (1) at the same time as the index referenced by the index-name associated with identifier-1 is incremented. Format 2. 7. The results of the SEARCH ALL operation are predictable only when: a. The data in the table is ordered in the same manner as described in the ASCENDING/DESCENDING KEY clause associated with the description of identifier-1, and: b. The contents of the key(s) referenced in the WHEN clause are sufficient to identify a unique table element. 8. If Format 2 of the SEARCH is used, a non-serial type of search operation can take place; the initial setting of the index-name for identifier-1 is ignored and its setting is varied during the search operation with the restriction that at no time is it set to a value that exceeds the value which corresponds to the last element of the table, or that is less than the value that corresponds to the first element of the table. The length of the table is discussed in the OCCURS clause. If any of the conditions specified in the WHEN clause cannot be satisfied for any setting of the index within the permitted range, control is passed to imperative-statement-1 of the AT END phrase, when specified, or to the next executable sentence when this phrase is not specified; in either case the final setting of the index is not predictable. If all conditions can be satisfied, the index indicates an occurrence that allows the conditions to be satisfied, and control passes to imperative-statement-2. 9. The index-name that is used for the search operation is the first (or only) index-name that appears in the INDEXED BY phrase of identifier-1. Any other index-names for identifier-1 remain unchanged. 10. For OSVS, VSC2 and MF only: Neither imperative-statement-2 nor NEXT SENTENCE is required. Without them, the SEARCH statement sets the index to the value in the table that matched the condition. Figure 4-5 shows a flowchart of the Format 1 SEARCH operation containing two WHEN phrases.Figure 4-5: Flowchart of SEARCH Operation Showing Two WHEN Phrases 1 - These operations are options included only when specified in the SEARCH statement. 2 - Each of these control transfers is to the next executable sentence unless the imperative-statement ends with a GO TO statement.
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