If DSAPI_MAX_POST_DATA_BUFF_SIZE is greater than DominoMultiPartPostBufferSize, than the maximum buffer size is set to DSAPI_MAX_POST_DATA_BUFF_SIZE.
By default, DSAPI_MAX_POST_DATA_BUFF_SIZE is set to 1 MB and cannot exceed 100 MB.
Therefore, DominoMultiPartPostBufferSize has a 10 MB minimum and a 100 MB maximum.
The default setting is 10 MB.