Do like this
add your commit work in Z function module
CALL FUNCTION 'ZPOSTING_INTERFACE_CLEARING' IN BACKGROUND TASK AS SEPARATE UNIT DESTINATION NONE
PERFORMING get_result ON END OF TASK
EXPORTING
I_AUGLV = 'UMBUCHNG'
I_TCODE = 'FB05'
I_SGFUNCT = 'C'
I_NO_AUTH = ' '
IMPORTING
* E_MSGID =
* E_MSGNO =
E_MSGTY = V_MSGTY
E_MSGV1 = V_MSGV1
E_MSGV2 = V_MSGV2
E_MSGV3 = V_MSGV3
E_MSGV4 = V_MSGV4
* E_SUBRC =
TABLES
T_BLNTAB = I_BLNTAB
T_FTCLEAR = I_FTCLEAR
T_FTPOST = I_FTPOST
T_FTTAX = I_FTTAX
EXCEPTIONS
CLEARING_PROCEDURE_INVALID = 1
CLEARING_PROCEDURE_MISSING = 2
TABLE_T041A_EMPTY = 3
TRANSACTION_CODE_INVALID = 4
AMOUNT_FORMAT_ERROR = 5
TOO_MANY_LINE_ITEMS = 6
COMPANY_CODE_INVALID = 7
SCREEN_NOT_FOUND = 8
NO_AUTHORIZATION = 9
OTHERS = 10
.
Wait until gv_flag = 'X'.
FORM GET_RESULT USING TASKNAME.
RECEIVE RESULTS FROM FUNCTION ZPOSTING_INTERFACE_CLEARING
IMPORTING
* E_MSGID =
* E_MSGNO =
E_MSGTY = V_MSGTY
E_MSGV1 = V_MSGV1
E_MSGV2 = V_MSGV2
E_MSGV3 = V_MSGV3
E_MSGV4 = V_MSGV4
gv_flag = 'X'.
ENDFORM.