HLASM Language Reference

COM Instruction
COM Instruction
The COM instruction identifies the beginning or continuation of a common control
section.
►►──┬────────┬──COM────────────────────────────────────────────────►◄
└─symbol─┘
symbol
is one of the following:
An ordinary symbol
A variable symbol that has been assigned a character string with a value
that is valid for an ordinary symbol
A sequence symbol
The COM instruction can be used anywhere in a source module after the ICTL
instruction.
If symbol denotes an ordinary symbol, the ordinary symbol identifies the common
control section. If several COM instructions within a source module have the same
symbol in the name field, the first occurrence initiates the common section and the
rest indicate the continuation of the common section. The ordinary symbol denoted
by symbol represents the address of the first byte in the common section, and has
a length attribute value of 1.
If symbol is not specified, or if name is a sequence symbol, the COM instruction
initiates, or indicates the continuation of, the unnamed common section.
See “CSECT Instruction” on page 123 for a discussion on the interaction between
COM and the GOFF assembler option.
The location counter for a common section is always set to an initial value of 0.
However, when an interrupted common control section is continued using the COM
instruction, the location counter last specified in that control section is continued.
If a common section with the same name (or unnamed) is specified in two or more
source modules, the amount of storage reserved for this common section is equal
to that required by the longest common section specified.
The source statements that follow a COM instruction belong to the common section
identified by that COM instruction.
Notes:
1. The assembler language statements that appear in a common control section
are not assembled into object code.
2. When establishing the addressability of a common section, the symbol in the
name field of the COM instruction, or any symbol defined in the common
section, can be specified in a USING instruction.
3. An AMODE cannot be assigned to a common section.
Chapter 5. Assembler Instruction Statements 121