Below is an example of an ABAP program tailored for SAP S/4HANA that selects records based on the specified SQL query, including input parameters for the report period and item number threshold on the selection screen, and displays the output in an ALV report using the CL_SALV_TABLE class.

Please adapt the program to meet your specific system and requirements as this is a generic template.

REPORT zsales_alv_report.

PARAMETERS: p_start TYPE sy-datum DEFAULT '20220101' OBLIGATORY,
            p_end   TYPE sy-datum DEFAULT '20221231' OBLIGATORY,
            p_thrsh TYPE i DEFAULT 10 OBLIGATORY.

TYPES: BEGIN OF ty_vbrp,
         vbeln      TYPE vbeln_va,
         itemcount  TYPE i,
       END OF ty_vbrp.

DATA: it_vbrp TYPE TABLE OF ty_vbrp,
      wa_vbrp TYPE ty_vbrp,
      go_alv   TYPE REF TO cl_salv_table.

START-OF-SELECTION.
  SELECT vbrp~vbeln, COUNT( DISTINCT posnr ) AS itemcount
    FROM vbrp
    INNER JOIN vbrk ON vbrp~vbeln = vbrk~vbeln
    WHERE vbrk~fkdat BETWEEN @p_start AND @p_end
    GROUP BY vbrp~vbeln
    HAVING COUNT( DISTINCT posnr ) > @p_thrsh
    ORDER BY itemcount DESCENDING
    INTO TABLE @it_vbrp.

  IF it_vbrp IS NOT INITIAL.
    TRY.
        cl_salv_table=>factory(
          IMPORTING
            r_salv_table = go_alv
          CHANGING
            t_table      = it_vbrp ).

      go_alv->display( ).
    CATCH cx_salv_msg INTO DATA(lx_msg).
      MESSAGE lx_msg TYPE 'I' DISPLAY LIKE 'E'.
    ENDTRY.
  ELSE.
    MESSAGE 'No data found for the selection criteria.' TYPE 'I'.
  ENDIF.

Remember to ensure that the provided date format in the default values matches what the user expects according to the locale. In the SAP system, the date format may vary based on the user's locale setting.

Additionally, ensure that the data types used above (vbeln_va, sy-datum, etc.) match the data types found in your system as these are common data types found in standard SAP ERP environments.

This program should be created using transaction SE38, SE80, or any other ABAP IDE like Eclipse with ADT installed. Once the program is created and saved in a package, it can be executed to generate an ALV report based on the given criteria.