iTS 1.0+)

Data Division

Compaq NonStop™ Pathway/iTS SCREEN COBOL Reference Manual—426750-001

5-18

SYNCHRONIZED Clause

When the aligned item (or table of aligned items) belongs to a higher-level table,

further adjustment might be necessary. If the elementary item is word-aligned

and the containing group occurrence consists of an odd number of character

positions, the compiler inserts one byte of FILLER data after each group

occurrence. If the item is doubleword aligned and the size of the containing

group occurrence is not a multiple of four, the compiler inserts the appropriate

amount of FILLER data (1, 2, or 3 bytes) after each group occurrence. In all

cases, inserted bytes are not part of the containing occurrences themselves, but

are included in group items that contain the complete table. The preceding

sequence is repeated for each higher-level table.

The following example illustrates alignment as it applies to multiple OCCURS clauses:

01 master.

02 table-1 OCCURS 5 TIMES.

03 table-2 OCCURS 5 TIMES.

04 table-3 OCCURS 5 TIMES.

05 item-a PIC 999 COMPUTATIONAL.

05 item-b PIC X.

04 item-3 PIC X.

03 item-2 PIC X.

Although master appears to occupy this many bytes:

(((2+1) * 5+1 ) * 5+1) * 5 = 405 bytes

it actually occupies:

((2+1+1) * 5+1+1) * 5+1+1) * 5 = 560 bytes

due to the alignment requirement for the COMPUTATIONAL item.

Implicit FILLER bytes must be accounted for in several situations. These bytes are

counted when determining the size of group items that contain them. Thus, when a data

item contains implicit FILLER bytes, the character positions of the bytes are included in

the allocation requirements of the item. Also, implicit FILLER bytes must be included

among the character positions redefined if a containing group item appears as the object

of a REDEFINES clause.

Automatic alignment or requested alignment of data items described by redefinition of

character positions (through use of the REDEFINES clause) follows the rules described

in the preceding paragraphs. However, when the first data item allocated by a

redefinition requires word alignment or doubleword alignment, the data item being

redefined must begin on the appropriate boundary. In other words, SCREEN COBOL

does not permit redefinitions that require insertion of implicit FILLER bytes before the

first data item of the redefinition. Any bytes inserted at other places within the

redefinition are counted when determining the redefinition size.