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HP OpenVMS Systems Documentation |
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HP COBOL
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If you specify an INVALID KEY phrase for a file and the I/O operation causes an INVALID KEY condition, the I/O system performs the associated imperative statement and no other file processing for the current statement. The Declarative USE procedure (if any) is not performed. The INVALID KEY phrase processes I/O errors due to invalid key conditions only.
If you do not specify an INVALID KEY phrase but declare a Declarative USE procedure for the file, the I/O system performs the Declarative USE procedure and returns control to the program.
If a severe error occurs and you do not have a Declarative Use procedure, your program will terminate abruptly with a run-time diagnostic. For example, given a program that looks for AFILE.DAT and that file is missing:
cobrtl: severe: file AFILE.DAT not found |
In this case, program run ends because you have not handled the error
with a Declarative Use procedure.
1.4.4 I/O Errors and RMS (OpenVMS)
I/O errors are detected by the I/O system, which (for OpenVMS systems) consists of Record Management Services (RMS) and the Run-Time Library (RTL). You can use the RMS special registers, which contain the primary and secondary RMS completion codes of an I/O operation, to detect errors. The RMS special registers are as follows:
RMS-STS
RMS-STV
RMS-FILENAME
RMS-CURRENT-STS
RMS-CURRENT-STV
RMS-CURRENT-FILENAME
Refer to the HP COBOL Reference Manual and the OpenVMS Record Management Services Reference Manual for more information about RMS special registers.
Examples 1-7 and 1-8 show how to use RMS special registers to detect errors.
| Example 1-7 Using RMS Special Registers to Detect Errors (OpenVMS) |
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IDENTIFICATION DIVISION.
PROGRAM-ID. RMSSPECREGS.
*
* This program demonstrates the use of RMS special registers to
* implement a different recovery for each of several errors with RMS files.
*
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT OPTIONAL EMP-FILE ASSIGN "SYS$DISK:ART.DAT".
SELECT REPORT-FILE ASSIGN "SYS$OUTPUT".
DATA DIVISION.
FILE SECTION.
FD EMP-FILE VALUE OF ID IS VAL-OF-ID.
01 EMP-RECORD.
02 EMP-ID PIC 9(7).
02 EMP-NAME PIC X(15).
02 EMP-ADDRESS PIC X(30).
FD REPORT-FILE REPORT IS RPT.
WORKING-STORAGE SECTION.
01 VAL-OF-ID PIC X(20).
01 RMS$_EOF PIC S9(9) COMP VALUE EXTERNAL RMS$_EOF.
01 SS$_BADFILENAME PIC S9(9) COMP VALUE EXTERNAL SS$_BADFILENAME.
01 RMS$_FNF PIC S9(9) COMP VALUE EXTERNAL RMS$_FNF.
01 RMS$_DNF PIC S9(9) COMP VALUE EXTERNAL RMS$_DNF.
01 RMS$_DEV PIC S9(9) COMP VALUE EXTERNAL RMS$_DEV.
01 D-DATE PIC 9(6).
01 EOF-SW PIC X.
88 E-O-F VALUE "E".
88 NOT-E-O-F VALUE "N".
01 VAL-OP-SW PIC X.
88 VALID-OP VALUE "V".
88 OP-FAILED VALUE "F".
01 OP PIC X.
88 OP-OPEN VALUE "O".
88 OP-CLOSE VALUE "C".
88 OP-READ VALUE "R".
REPORT SECTION.
RD RPT PAGE 26 LINES HEADING 1 FIRST DETAIL 5.
01 TYPE IS PAGE HEADING.
02 LINE IS PLUS 1.
03 COLUMN 1 PIC X(16) VALUE "Emplyee File on".
03 COLUMN 18 PIC 99/99/99 SOURCE D-DATE.
02 LINE IS PLUS 2.
03 COLUMN 2 PIC X(5) VALUE "Empid".
03 COLUMN 22 PIC X(4) VALUE "Name".
03 COLUMN 43 PIC X(7) VALUE "Address".
03 COLUMN 60 PIC X(4) VALUE "Page".
03 COLUMN 70 PIC ZZ9 SOURCE PAGE-COUNTER.
01 REPORT-LINE TYPE IS DETAIL.
02 LINE IS PLUS 1.
03 COLUMN IS 1 PIC 9(7) SOURCE EMP-ID.
03 COLUMN IS 20 PIC X(15) SOURCE IS EMP-NAME.
03 COLUMN IS 42 PIC X(30) SOURCE IS EMP-ADDRESS.
PROCEDURE DIVISION.
DECLARATIVES.
USE-SECT SECTION.
USE AFTER STANDARD ERROR PROCEDURE ON EMP-FILE.
CHECK-RMS-SPECIAL-REGISTERS.
SET OP-FAILED TO TRUE.
EVALUATE RMS-STS OF EMP-FILE TRUE
WHEN (RMS$_EOF) OP-READ
SET VALID-OP TO TRUE
SET E-O-F TO TRUE
WHEN (SS$_BADFILENAME) OP-OPEN
WHEN (RMS$_FNF) OP-OPEN
WHEN (RMS$_DNF) OP-OPEN
WHEN (RMS$_DEV) OP-OPEN
DISPLAY "File cannot be found or file spec is invalid"
DISPLAY RMS-FILENAME OF EMP-FILE
DISPLAY "Enter corrected file (control-Z to STOP RUN): "
WITH NO ADVANCING
ACCEPT VAL-OF-ID
AT END STOP RUN
END-ACCEPT
WHEN ANY OP-CLOSE
CONTINUE
WHEN ANY RMS-STS OF EMP-FILE IS SUCCESS
SET VALID-OP TO TRUE
WHEN OTHER
IF RMS-STV OF EMP-FILE NOT = ZERO
THEN
CALL "LIB$STOP" USING
BY VALUE RMS-STS OF EMP-FILE
END-IF
END-EVALUATE.
END DECLARATIVES.
MAIN-PROG SECTION.
000-DRIVER.
PERFORM 100-INITIALIZE.
PERFORM WITH TEST AFTER UNTIL E-O-F
GENERATE REPORT-LINE
READ EMP-FILE
END-PERFORM.
PERFORM 200-CLEANUP.
STOP RUN.
100-INITIALIZE.
ACCEPT D-DATE FROM DATE.
DISPLAY "Enter file spec of employee file: " WITH NO ADVANCING.
ACCEPT VAL-OF-ID.
PERFORM WITH TEST AFTER UNTIL VALID-OP
SET VALID-OP TO TRUE
SET OP-OPEN TO TRUE
OPEN INPUT EMP-FILE
IF OP-FAILED
THEN
SET OP-CLOSE TO TRUE
CLOSE EMP-FILE
END-IF
END-PERFORM.
OPEN OUTPUT REPORT-FILE.
INITIATE RPT.
SET NOT-E-O-F TO TRUE.
SET OP-READ TO TRUE.
READ EMP-FILE.
200-CLEANUP.
TERMINATE RPT.
SET OP-CLOSE TO TRUE.
CLOSE EMP-FILE REPORT-FILE.
END PROGRAM RMSSPECREGS.
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| Example 1-8 Using RMS-CURRENT Special Registers to Detect Errors (OpenVMS) |
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IDENTIFICATION DIVISION.
PROGRAM ID. RMS-CURRENT-SPEC-REGISTERS.
*
* This program demonstrates the use of RMS-CURRENT special registers
* to implement a single recovery for RMS file errors with multiple files.
*
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT FILE-1
ASSIGN TO "SYS$DISK:ART_1.DAT".
SELECT FILE-2
ASSIGN TO "SYS$DISK:ART_2.DAT".
SELECT FILE-3
ASSIGN TO "SYS$DISK:ART_3.DAT".
DATA DIVISION.
FILE SECTION.
FD FILE-1.
01 FILE-1-REC.
02 F1-REC-FIELD PIC 9(9).
FD FILE-2.
01 FILE-2-REC.
02 F2-REC-FIELD PIC 9(9).
FD FILE-3.
01 FILE-3-REC.
02 F3-REC-FIELD PIC 9(9).
PROCEDURE DIVISION.
DECLARATIVES.
USE-SECT SECTION.
USE AFTER STANDARD EXCEPTION PROCEDURE ON INPUT.
CHECK-RMS-CURRENT-REGISTERS.
DISPLAY "************** ERROR **************".
DISPLAY "Error on file: " RMS-CURRENT-FILENAME.
DISPLAY "Status Values:".
DISPLAY " RMS-STS = " RMS-CURRENT-STS WITH CONVERSION.
DISPLAY " RMS-STV = " RMS-CURRENT-STV WITH CONVERSION.
DISPLAY "***********************************".
END DECLARATIVES.
MAIN-PROG SECTION.
MAIN-PARA.
OPEN INPUT FILE-1.
OPEN INPUT FILE-2.
OPEN INPUT FILE-3.
.
.
.
CLOSE FILE-1.
CLOSE FILE-2.
CLOSE FILE-3.
STOP RUN.
END-PROGRAM RMS-CURRENT-SPEC-REGISTERS. <>
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1.5 Using Program Switches
You can control program execution by defining switches
in your HP COBOL program and setting them internally (from within
the image) or externally (from outside the image). Switches exist as
the environment variable COBOL_SWITCHES (on the Tru64 UNIX operating system) or the
logical name COB$SWITCHES (on the OpenVMS operating system).
On OpenVMS systems, switches can be defined for the image, process, group, or system. <>
On Tru64 UNIX systems, switches can be defined for the image or
process. <>
1.5.1 Setting and Controlling Switches Internally
To set switches from within the image, define them in the SPECIAL-NAMES paragraph of the ENVIRONMENT DIVISION and use the SET statement in the PROCEDURE DIVISION to specify switches ON or OFF, as in the following example:
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SPECIAL-NAMES.
SWITCH 10 IS MY-SWITCH
ON IS SWITCH-ON
OFF IS SWITCH-OFF.
.
.
.
PROCEDURE DIVISION.
000-SET-SWITCH.
SET MY-SWITCH TO ON.
IF SWITCH-ON
THEN
DISPLAY "Switch 10 is on".
.
.
.
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On OpenVMS systems, SET in COBOL will attempt to write a user mode logical name (COB$SWITCHES) to the first entry in the LNM$FILE_DEV chain. It will therefore fail if that logical name table denies WRITE access.
To change the status of internal switches during execution, turn them on or off from within your program. However, be aware that this information is not saved between runs of the program.
Refer to the HP COBOL Reference Manual for more information about setting internal switches.
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