Package com.softwaremining.ims.interfaces

Interface IPCBDatabase

All Superinterfaces:
AbstractDataObject, IProgramControlBlock, ISMDataType
All Known Implementing Classes:
PCBDatabase
public interface IPCBDatabase extends IProgramControlBlock
Program Control Block fort database operations (reading/writing SEGMENTS/Tables. This is a per-segment control structure to pass to every DL/I call in IMS Program. It serves two main purpose:
Control & Status
  • Holds the status of each DL/I operation (e.g. end-of-data, errors) via status fields (LTERM, STAT-CODE).
  • Carries control information such as record length, key length or overflow indicators if you're doing keyed or positional access.

Buffer Addressing
  • Contains pointers-or is overlaid on your COBOL data area-that tell IMS where to read segment data into (for GETs) or from (for PUTs/REPLACEs).
  • By passing the same PCB into each CALL 'CBLTDLI', IMS knows which segment you're working on and where in memory your segment buffer lives.