COBOL Manual for TNS/E Programs (H06.08+, J06.03+)

when you have finished working with it, because merely purging the file does not erase the data
from the disk.
The HP COBOL library routine COBOL_CONTROL_ is a multipurpose routine that calls the operating
system routine CONTROL, and whose function is determined by an operation code. The operation
code 20 enables a process to purge only the contents of a file if the process has write access to
the file. The process can even purge the data from a temporary file whose name was assigned by
Enscribe because you specified only a volume name or assigned it to #TEMP.
The COBOL_CONTROL_ routine call for purging data requires two parameters. The first parameter
is the file-name described in the SELECT clause of the file-control entry for the file; the second
is the number 20 (which causes the file system to purge the data in the file). Example:
ENTER "COBOL_CONTROL_" USING MYFILE 20
For more information about the CONTROL routine, see the Guardian Procedure Calls Reference
Manual.
Renaming a File From an HP COBOL Program
The FILE_RENAME_ procedure enables a process to rename a closed disk file, provided the process
has purge access to the file. If the file is a temporary file, the process can call FILE_RENAME_ to
make the file a permanent file. For more information about the RENAME or FILE_RENAME_ routine,
see the Guardian Procedure Calls Reference Manual.
Creating a File Having Alternate Keys From an HP COBOL Program
At times, it is necessary within an HP COBOL process to create and operate on a file that has
alternate keys. Suppose the file must be named and built during execution. The only way to do
this is through a series of steps involving a few Enscribe routines:
1. Declare the records of the file in a file description entry.
2. Use the FILE_CREATELIST_ procedure to create the primary file in conformance with the
specification in the file-control entry and the file description.
3. Use the FILE_CREATELIST_ procedure to create the alternate-key file in conformance with the
specification of the keys in the file-control entry and the record description for the file.
4. Open the loadfile and use it.
Suppose you have a server process that must create a private, indexed file having one alternate
key.
NOTE: This explanation does not elaborate all the data definitions and all the code necessary
to manage the creation of an indexed file with an alternate key. Only the significant declarations
and code are shown. In some cases, the code mentions data items that are presumed to have been
defined and given values by statements not shown.
The file-control entry and file description entry are:
SELECT T-file-1 ASSIGN TO "ISFILE"
ORGANIZATION IS INDEXED
RECORD KEY IS K1
ALTERNATE RECORD KEY IS AK1
ACCESS MODE IS DYNAMIC
FILE STATUS IS Fs
...
FD T-file-1 LABEL RECORDS OMITTED.
01 T-rec-1.
02 K1.
03 K1-fp PIC XX.
03 FILLER PIC X.
02 Ak1.
03 Fp PIC X(5).
03 Lp PIC X(5).
02 FILLER PIC X(20).
886 Disk Input and Output