ISPF can run up to 32 logical screens at one time. You can specify the maximum number of logical screens allowed for your installation by modifying the ISPF configuration table. See The ISPF Configuration Table for more information about modifying the ISPF configuration table. Set the value of keyword MAXIMUM_NUMBER_OF_SPLIT_SCREENS to any number from 4 to 32. The default value is 8. Be sure to consider your users' region size when you set the limit for the maximum number of screens.