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Range of a labeled USING instruction HLASM Language Reference SC26-4940-06 |
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The range of a labeled USING instruction (called the labeled USING range) is the 4096 bytes beginning at the base address specified in the labeled USING instruction, or the range as specified by the range end, whichever is the lesser. Addresses that lie within the labeled USING range can be converted from their implicit form (qualified symbols) to their explicit form; those outside the USING range cannot be converted. Like the ordinary USING range, the labeled USING range is the range
of addresses in a control section that is associated with the base
register specified in the labeled USING instruction. If the labeled
USING instruction assigns more than one base register, the composite
labeled USING range is the product of the number of registers specified
in the labeled USING instruction and 4096 bytes. The composite labeled
USING range begins at the base address specified in the labeled USING
instruction. Unlike the ordinary USING range, however, you cannot
specify separate labeled USING instructions to establish the same
labeled USING range. For example,
specifies
a range of 8192 bytes beginning at BASE, but
specifies a single labeled USING
range of 4096 bytes beginning at BASE+4096.You can specify the same base address in any number of labeled
USING instructions. You can also specify the same base address in
an ordinary USING and a labeled USING. However, unlike ordinary USING
instructions that have the same base address, if you specify the same
base address in an ordinary USING instruction and a labeled USING
instruction, High Level Assembler does not treat the USING ranges
as coinciding. When you specify an unqualified symbol in an assembler
instruction, the base register specified in the ordinary USING is
used by the assembler to resolve the address into base-displacement
form. Here is an example of coexistent ordinary USINGs and labeled
USINGs:
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. |
Copyright IBM Corporation 1990, 2014
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