Number of open full-function database data sets

IMS does not enforce a limit on the number of full-function database data sets that can be open at the same time by multiple databases. However, the resources available at your installation and the consumption of those resources by both your IMS configuration and the other z/OS® subsystems that your installation might be running, such as Db2 for z/OS, could potentially limit the number of data sets that you can open.

For full-function databases, one of the resources that could become constrained with a large number of open data sets is the private storage of the DL/I separate address space (DLISAS), which requires storage both above and below the 16 MB line.