The value specifies the size of the roll area in bytes. The roll area is one of several memory areas, which satisfies the user requests of user programs.  For technical reasons, however, the first 250 KB or so of a user context are always stored in the roll area, further data.

– up to the roll area limit ztta/roll_first,

– in the extended memory, up to the limit ztta/roll_extension or if extended memory is exhausted, then

– again in the roll area, until the roll area is full, then

– in the local process area, up to the limit abap/heap_area_dia or abap/heap_area_total or until the address space or the swap space is exhausted.

Followed by termination with errors like STORAGE_PARAMETERS_WRONG_SET an error code, that points to memory bottleneck Minimum data transfer with context change; however, the increase helps to avoid problems (address space, swap space, operating system paging).