Fill characters for output device fields

MFS uses fill characters to pad output device fields when the length of the data received from the application program is less than the specified length or no data for the field is received.

A fill character is defined in the message definition (MSG statement), the format definition (DPAGE statement), or both. If a fill character is specified in both, the fill character specified in the DPAGE is used. If FILL=NONE is specified in the DPAGE statement, the fill character from the MSG statement is used. The fill character specified in the MSG statement is used for all nonliteral fields defined in the DOF, not just those defined by MFLDs in the MOD. Using a fill character tailored to the device type generally improves message presentation and device performance. You can select the following fill characters on a DPAGE statement:

You can select the following characters on a MSG statement:

For the 3270 or SLU 2 display, the EBCDIC graphic fill character fills in any fields or partial fields on the formatted display that do not receive any data or only partial data. This erases information remaining on the display from the previous message, however, using the fill character increases transmission time.

Null fill can be specified, in which case fields are not filled on the 3270 or SLU 2 formatted screen (and data from the previous message that is not updated by the current message is still displayed). For devices other than 3270 or SLU 2 display, compacted lines are produced when message data does not fill device fields. Using null fill for 3270 or SLU 2 display devices reduces transmission time, but might result in confusion if a partial field does not cover all the data remaining from a previous display. Using null fill for other devices causes additional processing in the IMS control region but reduces transmission and printing time.

For 3270 or SLU 2 formatted screen, a program tab function can be requested that erases any data remaining in a device field after new data for this field has been displayed, but does not produce any fill characters. With program tab fill, display fields on a formatted screen are not cleared unless new data is transmitted to them.

When the program sends only a few of the output data fields, the unwanted display of leftover data in unprotected fields can be prevented by specifying the erase all unprotected function in the system control area (SCA).

For 3270 output when EGCS fields are present, specify only FILL=PT or FILL=NULL on the DPAGE or MSG statement. Any other specification can result in the device rejecting the message.