Inserting segments using field-level sensitivity

The TYPE= parameter on the SEGM statement of the DBD determines the fill value in the physical segment when an application program is not sensitive to a field on insert calls.

TYPE=
Fill Value
X
Binary Zeros
P
Packed Decimal Zero
C
Blanks

The fill value in the physical segment is binary zeros when:

  • Space in a segment is not defined by a FIELD macro in the DBD
  • A defined DBD field is not referenced on the insert operation

The following figure shows an example of an insert operation based on the DBD and PCB in Figure 1.

Figure 1. Example of an ISRT call
In I/O area: EMPNAME is Adams, Dick; EMPNO is 23456; and ADDRESS is Vermont. After update, physical segment has these three fields. BIRTHD and SAL fields not specified.

Blanks are inserted in the BIRTHD field because its FIELD statement in the DBD specifies TYPE=C. Packed decimal zero is inserted in the SAL field because its FIELD statement in the DBD specifies TYPE=P. Binary zeros are inserted in positions 35 to 40 because no FIELD statement was coded for this space in the DBD.