abap/heap_area_nondia is a SAP Parameter attribute which is used to control limit of heap memory per non dialog work process information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Specifies the maximum local process memory (heap, malloc) that can be allocated to one non-dialog work process (update, spool, background work process). The aim is to limit the size of a user context if required.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.