HLASM Language Reference

USING Instruction
In this MVC instruction, the (unqualified) first operand is resolved with the ordinary
USING, and the (qualified) second operand is resolved with the labeled USING.
Domain of a Labeled USING Instruction
The domain of a labeled USING instruction (called the labeled USING domain)
begins where the USING instruction appears in a source module. It continues to
the end of the source module, except when:
A subsequent DROP instruction specifies the label used in the preceding
labeled USING instruction.
A subsequent USING instruction specifies the same label used in the preceding
labeled USING instruction. The second specification of the label causes the
assembler to end the domain of the prior USING with the same label.
You can specify the same base register or registers in any number of labeled
USING instructions. However, unlike ordinary USING instructions, as long as all
the labeled USINGs have unique labels, the assembler considers the domains of all
the labeled USINGs to be active and their labels eligible to be used as symbol
qualifiers. With ordinary USINGs, when you specify the same base register in a
subsequent USING instruction, the domain of the prior USING is ended.
The assembler converts implicit address references into their explicit form using the
base register or registers specified in a labeled USING instruction when the
following conditions are met:
The address reference appears in the domain of the labeled USING instruction.
The address reference takes the form of a qualified symbol and the qualifier is
the label of the labeled USING instruction.
| The address lies within the range of the labeled USING instruction.
Dependent USING Instruction
The dependent USING instruction format specifies a base address and a
relocatable expression instead of one or more base registers. If a USING label is
also specified, this format USING instruction is called a labeled dependent USING
instruction.
Dependent USING
►►───┬─────────────────┬─USING─┬─base─────────────
┬─,address───────►◄
├─label───────────┤
└─(base─┬────── ┬─)
─┘
└─sequence_symbol─┘
└─,end─┘
label
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
sequence_symbol
is a sequence symbol.
226 HLASM V1R5 Language Reference