FKK_NO_BUFFER_SET is a standard SAP function module that performs functionality. This is available within standard R/3 SAP systems depending on version and release level.
Below are the pattern details for this FM showing its interface including any import, export and tables parameters. There is also a list of Exceptions and for your convenience any standard documentation available. All this information and more can also be viewed if you enter the function module name FKK_NO_BUFFER_SET into the relevant SAP transaction such as SE37 or SE80.
CALL FUNCTION 'FKK_NO_BUFFER_SET' "
* EXPORTING
* i_no_buffer = " xfeld
. " FKK_NO_BUFFER_SET