The POPULATION (or MAXENTRIES) option specifies the expected size of the set or subset.

For disjoint sets or subsets, the population indicates the number of entries which the structure is expected to contain.

For embedded sets or subsets, the population indicates the average number of entries for each master. The population does not limit the number of entries for each owner; some owners can reference substantially more records than the population specifies, while others refer to no records.

When a set or subset declaration does not specify a population, a default population is computed. Sets, automatic subsets, and manual subsets which reference data sets declared at the same level inherit the population of the data set they reference. Manual subsets which reference data sets declared at a higher level are assigned a default population of 10 for each owner record.

When a population is specified but areas and area size are not, the system computes a default value for areas and area size based on the specified population. When population and areas are specified, the system uses these values to compute the area size. Similarly, the system computes the areas if population and area size are stipulated. The value designated for the population is ignored if both areas and area size are specified.

The maximum population value, with the exception of an embedded data set, is 549,755,813,887 records. An embedded data set has a maximum population value of 268,435,455 records. If the computed population value exceeds the maximum, the system displays a warning message and places the maximum value in the description file. However, the listing prints the POPULATION value, which is based on the value of AREAS multiplied by AREASIZE multiplied by number of sections. If the population is greater than 268,435,455 records, then sections specifications is required.