HLASM Language Reference

USING Instruction
LEFT USING ELEMENT,R3
RIGHT USING ELEMENT,R6
NEW USING ELEMENT,R1
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MVC NEW.RPTR,LEFT.RPTR Move previous Right pointer
MVC NEW.LPTR,RIGHT.LPTR Move previous Left pointer
ST R1,LEFT.RPTR Chain new element from Left
ST R1,RIGHT.LPTR Chain new element from Right
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ELEMENT DSECT
LPTR DS A Link to left element
RPTR DS A Link to right element
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Range of a Labeled USING Instruction
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,
| IN USING BASE,1,11
| specifies a range of 8192 bytes beginning at BASE, but
| IN USING BASE,1
| IN USING BASE+496,11
| 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. An example of
coexistent ordinary USINGs and labeled USINGs is given below:
USING IHADCB,R1
SAMPLE USING IHADCB,R2
MVC DCBLRECL,SAMPLE.DCBLRECL
Chapter 5. Assembler Instruction Statements 225