Consider the following issues when writing your application.
Each site can add its own list of properties to the pools configuration.
Multiple configurations can be maintained in multiple configuration files. The system administrator can commit different files to reflect changes to the resource consumption at different time slots. These time slots can include different times of the day, week, month, or seasons depending on load conditions.
Resource sets can be shared between pools, but a pool has only one resource set of a given type. So, the pset_default can be shared between the default and a particular application's database pools.
Use pool_value_*() interfaces carefully. Keep in mind the memory allocation issues for string pool values. See Report Pool Statistics for a Given Pool.