IMS DB – Control Blocks IMS Control Blocks define the structure of the IMS database and a program”s access to them. The following diagram shows the structure of IMS control blocks. DL/I uses the following three types of Control Blocks − Database Descriptor (DBD) Program Specification Block (PSB) Access Control Block (ACB) Database Descriptor (DBD) […]
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IMS DB – DL/I Terminology Hierarchical databases work on the relationships between two or more segments. The following example shows how segments are related to each other in the IMS database structure. Root Segment Points to note − The segment that lies at the top of the hierarchy is called the root segment. The root […]
IMS DB – Cobol Basics We include DL/I calls inside COBOL application program to communicate with IMS database. We use the following DL/I statements in COBOL program to access the database − Entry Statement Goback Statement Call Statement Entry Statement It is used to pass the control from the DL/I to the COBOL program. Here […]