The gateway system identifier (SID) is an alphanumeric character string that identifies a gateway instance. If you want to connect simultaneously to different data sources, you need one gateway instance, and therefore one gateway SID, for each database you are accessing. The SID name is used as part of the file name for the initialization parameter file. The default SIDs are as follows:
- Adabas: tg4adbs
- IMS: tg4ims
- VSAM: tg4vsam
If you want to access a different data source at a time, you can to set the HS_FDS_DATASOURCE_NAME parameter in the initialization parameter file instead of defining different SIDs.
If you have one data source and want to access it sometimes with one set of gateway parameter settings, and other times with different gateway parameter settings, you can do that by defining two different data sources and defining the matching SIDs accordingly.