Operational Control Language
Operational Control Language (OCL) is the control language of the IBM System/34 and System/36 minicomputer family. Other control languages include CL (System/38 and AS/400), JCL (System/370), and REXX (AS/400). The facility of DOS to use batch files is also control language.
On the IBM S/34 and S/36, OCL statements are used to directly load user or system programs into memory, assign system resources to them, and transfer system control to them in a process called execution. The fact that a program is on a computer's disk drive does not in itself cause the computer to begin working on the program.
OCL statements can be entered from the keyboard, but are generally stored in a S/34-S/36 procedure member. A procedure member is a freely editable member within a library, not dissimilar from a source member. On the S/34-S/36, procedures are not compiled.
OCL statements begin with two slashes and a space. Here's an example of a short procedure stored on a System/36 as PROC1:
** Procedure PROC1
**
** Written by Joe User 2006-05-29
**
**
// * 'PROC1 procedure is running'
// * ' '
// IFF ACTIVE-'PROC2,PROC3' GOTO OKAY
** IFF means 'if false'
** ACTIVE-'nnn,nnn2' means at least one of the listed programs is currently running
** GOTO xxx means skip to the statement that says TAG xxx and resume processing
// PAUSE ' Cannot continue because other Payroll is running'
// CANCEL stops execution of this procedure
// TAG OKAY
// IFF DATAF1-PFILE1 IFF DATAF1-PFILE2 GOTO NODELT
// * ' Caution, Pay Data Exists' displays info on CRT
// * ' '
// * ' Press 1 to continue and DELETE existing files'
// IFF '1'=?1R? CANCEL A parameter is indicated by question marks surrounding a number
** Using 1R between question marks indicates that the parameter is required and processing
** waits for user input. CANCEL means immediately go to end of job.
// LOAD $DELET $DELET is used to delete files
// RUN
// IF DATAF1-PFILE1 SCRATCH UNIT-F1,LABEL-PFILE1 deletes a disk file
// IF DATAF1-PFILE2 SCRATCH UNIT-F1,LABEL-PFILE2
// END END returns control from a system program
// LOAD PR101 PR101 is the sample RPG program
// FILE NAME-PAYMAST,DISP-SHR PAYMAST is the payroll master file
// FILE NAME-PFILE1,DISP-NEW,RECORDS-100,EXTEND-100 A new file PFILE1 is created
** 100 records are assigned to PFILE1 - if full, the system tries to extend it by another 100
** each time it fills.
// RUN
** It's not necessary or valid to put an END statement after most user programs
// SWITCH 1XXXXXXX Causes U1 to be SETON in the RPG program
// LOCAL OFFSET-1,DATA-'PROC1' Places PROC1 in the Local Data Area
// LOCAL OFFSET-101,DATA-'?USER?' Substitutes the operator's User ID
** LDA becomes the external data structure (UDS) in an RPG program
// LOAD PR102
// FILE NAME-PAYMAST,DISP-SHR DISP-SHR means the file is shared
** Other programs can use PAYMAST at the same time
// FILE NAME-PFILE,LABEL-PFILE1
** NAME/LABEL is used when the RPG disk file and the actual disk file names are different.
// RUN
// RETURN Return means go to end-of-job
In this short procedure, a number of OCL statements and procedure control expressions (PCE) are used. Comments are represented by an asterisk in column 1, or can be placed after the end of a statement.