IMS DB Segment Search Arguments
Segment Search Arguments used to push IMS to correct segment by supplying details such as segment name and key values.
SSA parameters are optional parameters.
SSA parameters required depending on the type of the call issued.
They are used to search data segments inside the IMS database.
SSAs allow the application program to define the type of database access required to IMS.
There are two types of calls to IMS:
The application program provides an SSA describes to IMS what segment needs to access.
For Qualified calls there are two types of SSAs.
In qualified SSA, more information will be provided along with the segment name is provided by the application program.
Additional parameters will be passed always along with segment name.
Qualified SSA can be explained in detail here
In unqualified SSA, Only the segment name is provided by the application program.
The Segment name can be passed during the call.
Unqualified call can be explained in detail here
The application does not provide an SSA.
IMS will determine what segment to process.
For retrieval calls, IMS reads the next segment in the database from the current position in IMS database.
For update call, IMS processes the segment which has been held the lock.
IMSDB IO Area IMSDB Unqualified SSA