The following example shows the structure of a COBOL program that uses IMS database and DL/I calls.
IMS COBOL LANGUAGE REFERENCE MANUAL CODE
The program can use this code to determine whether the call succeeded or failed.įor more understanding of COBOL, you can go through our COBOL tutorial here. It is the name of an interface module that is link edited with your program’s object module.Īfter each DL/I call, the DLI stores a status code in the PCB. Given below are the points to note about the Call statement −ĬBLTDLI stands for COBOL to DL/I. They are used to search data segments inside the IMS database. These are optional parameters depending on the type of the call issued. This is an area of the application program into which the DL/I puts a requested segment. No SELECT, ASSIGN, OPEN, or CLOSE statements are required. The PCB definition inside the Linkage Section is called as PCB Mask. This argument is the name of the four character fields that describe the I/O operation. Identifies the DL/I function to be performed. We will discuss each of them in the following table − S.No. The syntax above shows parameters which you can use with the call statement. Here is the syntax of the call statement − That is why, in DL/I application programs, Goback statement is used.īefore issuing a Goback statement, all the non-DL/I datasets used in the COBOL application program must be closed, otherwise the program will terminate abnormally.Ĭall statement is used to request for DL/I services such as executing certain operations on the IMS database.
If we use STOP RUN, the DL/I never gets a chance to perform its terminating functions. We should not use STOP RUN as it returns the control to the operating system. It returns the control to DL/I from the program. GOBACK is coded at the end of the application program. Listed below are the fundamental points to note about the Goback statement − Following is the syntax of the Goback statement − It is used to pass the control back to the IMS control program. The sequence of listing in the entry statement should be same as they appear in the PSBGEN. The relation between PCB masks and actual PCBs in storage is created by listing the PCBs in the entry statement. Likewise, when the DL/I gives the control to the application program, it also provides the address of each PCB defined in the program's PSB.Īll the PCBs used in the application program must be defined inside the Linkage Section of the COBOL program because PCB resides outside the application program.
When we call a sub-program in COBOL, its address is also provided.
The entry statement is used to define the entry point in the program. The DL/I loads the required control blocks and modules and the application program, and control is given to the application program.ĭLITCBL stands for DL/I to COBOL. The batch initialization module triggers the application program and is executed under its control. Let us go into the details of the entry statement in COBOL program − The above statement is coded in the Procedure Division of a COBOL program. Here is the syntax of the entry statement − It is used to pass the control from the DL/I to the COBOL program. We use the following DL/I statements in COBOL program to access the database − We include DL/I calls inside COBOL application program to communicate with IMS database.
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