IMS DB Management Calls
DL/I calls used to perform data management functions with IMS DB in application program.
Data management function can perform operations like READ, INSERT and INSERT etc,.
Database calls must be either DB PCBs or AIB parameters (which will be discussed in further topics).
The below is the list of functions that can be performed on the database.
|Function Code||Meaning and Use Options|
|GN||Get Next Segment in sequential order
Retrieves subsequent segments sequentially.
Call with Get Next (GN) is used to retrieve segments sequentially from the database.
|GNP||Get Hold Next segment in Parent
Retrieves dependent segments sequentially.
Call with Get Next in Parent (GNP) is used to retrieve dependent segments sequentially.
|GHN||Get Hold Next Segment.
Retrieves subsequent segments from the database
Call with Get Hold Next (GHN) is the holding segment for a GN call.
|GHNP||Get Hold Next segment in Parent
Retrieves dependents sequentially.
Call with Get Hold Next in Parent (GHNP) is the hold segment for the GNP call.
|GU||Get Unique Segment.
Retrieves unique segments and establishes a starting position in the database
Call with Get Unique (GU) is used to directly retrieve segments.
And also to establish the starting position in the database for sequential processing.
|GHU||Get Hold Unique Segment
Retrieves matching segments and establishes a starting position in the database.
Call with Get Hold Unique (GHU) is the hold segment for a GU call.
|ISRT||To insert the segment.
Used to loads and adds one or more segments to the database
The Insert (ISRT) call is used to load a database and to add one or more segments to the database.
And also ISRT used to add a record to the end of a GSAM database.
|REPL||Replace the segment.
Changes values of one or more fields in a segment.
The Replace (REPL) call is used to change the values of one or more fields in specified segment.
|RLSE||Release Locks on Segment.
Releases all locks held for unmodified data.
The Release Locks (RLSE) call is used to release all locks held for unmodified data.
Removes specified segment
It also removes all its dependents from the database
IMSDB Command Codes IMSDB Functions