DFHM32 (3270 mapping)

The 3270 mapping program (DFHM32) is called in response to requests for BMS services involving terminals of the 3270 Information Display System. Figure 1 shows how the 3270 mapping program responds to these requests.
Figure 1. 3270 mapping program interfaces
Diagram showing how DFHM32, the 3270 mapping program, responds to requests for BMS services involving 3270 terminals
Note:
  1. The following types of requests by an application program communicating with an IBM 3270 Information Display System passes information through the TCA by way of the mapping control program (DFHMCP) and the page and text build program (DFHPBP) to DFHM32:
    • SEND MAP ACCUM
    • SEND MAP PAGING
    • SEND MAP SET
    • SEND TEXT
    • SEND TEXT ACCUM
    • SEND TEXT PAGING
    • SEND TEXT SET

    For one page of output, DFHM32 acquires an area and formats it into a chain of control blocks known as map control areas (MCAs). Each MCA corresponds to one map on the page and contains information for chaining down the maps and processing the fields in each map. DFHM32 then builds the data stream directly from the maps and the TIOAs.

  2. A RECEIVE MAP or RECEIVE MAP FROM request by an application program communicating with an IBM 3270 Information Display System passes information through the TCA through the message control program (DFHMCP) to DFHM32.
  3. Maps are either passed by the application program or loaded by DFHMCP.
  4. DFHM32 communicates with storage control to obtain and release storage for MCAs and for the mapped data.
  5. All output requests (see note 1) are sent to a designated destination by the terminal page processor (DFHTPP) after control is returned to DFHPBP.