PH42816: SUPPORT LOWER AND UPPER LIMITS ON USING INSTRUCTION

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• Provide a way to limit the lower and upper addressability limits
  on the USING instruction, applying to instructions which use
  long displacements as well as 12-bit displacements.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of HLASM for z/OS, z/VM, z/VSE and     *
  *                 Linux                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: Support lower and upper limit values    *
  *                      for the USING instruction.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  There is no way to limit the range of locations which can be
  addressed by a long displacement instruction via a specific
  USING statement.
  
  For consistency, any such limit should also apply in the same
  way to standard displacement instructions if the limit values
  lie within the range of such instructions.
  
  The solution should also allow multiple discontiguous areas to
  be based on the same set of base registers.
  

Problem conclusion

Temporary fix

Comments

• The USING instruction now supports optional lower and upper
  limit suboperands to restrict the range of addressability,
  in addition to the existing end limit which only applies for
  12-bit displacements.
  
    USING (base,end,lower,upper),...
  
  The parentheses are only needed if more than one suboperand is
  specified.  Trailing commas are optional if trailing suboperands
  are unused.
  
  The lower and upper suboperands specify addressability range
  limits for this USING statement, regardless of whether a
  standard or long displacement is being used.  Both must be
  locations within the same relocatable area as the base address,
  and can have either a positive or negative offset from the base.
  
  The lower limit specifies the first location that can be
  addressed using this USING statement, and the upper limit
  specifies the end of the area which can be addressed (as for the
  existing 12-bit end limit option), which is one byte beyond the
  last addressable location.
  
  It is an error if the lower value is greater than or equal to
  the upper value.
  
  The lower and upper locations are not necessarily addressable in
  practice, even by long displacement instructions.  They are only
  used to establish the maximum addressability range.
  
  For an ordinary USING or non-dependent labeled USING, the
  default is that no limit applies, which is represented by the
  relevant limit being set to the base address plus x'80000000'.
  For the lower limit, this is simply treated as the most negative
  number.  For the upper limit, when the value is decremented by
  one, wrapping round to positive, this gives the highest
  addressable offset as x'7FFFFFFF', the maximum possible.
  
  For a dependent USING, the defaults are inherited from the
  supporting base USING.
  
  These limits allow the same base registers to be used to address
  multiple discontiguous parts of the same section, for example as
  follows:
  
    USING (codebase,,code,code_end),R3,R4,R5
    USING (codebase,,static,static_end),codebase
    USING (codebase,,literals,literals_end),codebase
  
  The Active Usings headings now include the lower and upper
  limits in the range information if present, shown as signed
  hexadecimal offsets relative to the location addressed by the
  first base register.
  
  In the Using Map report, if a lower or upper limit is present,
  the first line for a USING instruction is followed by an
  additional line showing any lower limit under the Value column
  and any upper limit under the Range column.  Both values are
  relative to the location addressed by the first base register.
  
  In some cases the Using Map for a dependent USING incorrectly
  showed a default range (00001000 for 4K bytes) instead of either
  showing zero (if the range start address is not addressable
  using a 12-bit displacement) or the remaining range from the
  dependent USING offset to the end of the 12-bit addressability
  range.  This has been corrected.
  
  The ADATA USING Map record has not been changed at present as it
  would require an incompatible update to add the new information.
  
  DOCUMENTATION UPDATES:
  
  In the HLASM Language Reference, SC26-4940-09, the description
  of each of the three forms of the USING instruction (Ordinary
  USING, Labeled USING and Dependent USING) is updated as follows:
  
  In the syntax diagram, optional positional suboperands are added
  for the lower and upper limit suboperands following the end
  limit, where the commas are only required if any following
  suboperand is used.
  
    (base,end,lower,upper)
  
  The descriptions of the lower and upper limits are added
  following the end limit as follows:
  
   lower
     Specifies a lower limit for the addressability range, which
     applies both for 12-bit displacements and for long
     displacements.  The lower limit must have the same
     relocatability attribute as the base and can have any
     negative or positive offset from the location addressed by
     the first base register.  An offset of x'80000000' is
     equivalent to no limit.
  
   upper
     Specifies an upper limit for the addressability range, which
     applies both for 12-bit displacement and for long
     displacements.  This is one more than the maximum addressable
     byte address, as for the end limit.  The upper limit must
     have the same relocatability attribute as the base and can
     have any negative or positive offset from the location
     addressed by the first base register, but if a lower limit is
     present the upper limit must be greater than the lower limit.
     An offset of x'80000000' is equivalent to no limit.
  
  The first paragraph following the heading "Range of an ordinary
  USING instruction" is replaced with the following three
  paragraphs:
  
   For instructions with 12-bit displacements, the maximum range
   of an ordinary USING instruction (called the "ordinary USING
   range", or the "USING range") is the 4096 bytes beginning at
   the base address specified in the USING instruction.  For
   long-displacement instructions, the maximum range is the
   addresses between (base_address-524288) and
   (base_address+524287).
  
   The range for 12-bit displacements may be limited by specifying
   an end limit address which is less than the end of the maximum
   range.  The range for both types of displacement may be limited
   by specifying lower and upper limit values.
  
   Addresses that lie within the USING range can be converted from
   their implicit to their explicit base-displacement form using
   the designated base registers; those outside the USING range
   cannot be converted.
  
  In the HLASM Programmer's Guide, SC26-4941-07, the following
  changes are made:
  
  In the "Source and object" section point 16 of the Active
  Usings headings is modified to show the range in the form
  (range,lower,upper) if a lower or upper limit is present.
  The lower and upper limits are shown as hexadecimal offsets
  from the location addressed by the first base register.
  
  In the "USING map" section a new example will be provided with
  lower limit (13) and upper limit (14) immediately below fields
  (6) for the value and (7) for the range.  These are documented
  in additional points as follows:
  
   (13)
     For a USING statement which specified a lower limit, this
     shows the lower limit relative to the location addressed
     by the first base register.
  
   (14)
     For a USING statement which specified an upper limit, this
     shows the upper limit relative to the location addressed
     by the first base register.
  
  The documentation of message ASMA313E is modified to cover
  the case where it applies to the upper and lower limits, and
  to correct the system action:
  
   ASMA313E The end value specified in the USING is less than or
            equal to the start value
  
   Explanation
     The end limit value specified is less than or equal to the
     base value, or the upper limit value is less than or equal to
     the lower limit value, which results in a zero or negative
     range.
  
   System action
     The statement is ignored.
  
  The documentation of message ASMA314E is modified to refer
  to "limit" instead of "end" throughout, and the explanation
  is modified, as follows:
  
   ASMA314E The base and limit values have differing relocation
            attributes
  
   Explanation
     The base value and the end limit, lower limit or upper limit
     value have differing relocation attributes; that is, they are
     defined in different sections.
  
   System action
     The statement is ignored.
  
   Programmer response
     Change the USING statement to specify a limit value that is
     in the same section as the base value.
  
  END OF DOCUMENTATION UPDATES
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI78977 UI78978 UI78979

Modules/Macros

•    ASMAINFO ASMA2F   ASMA2G   ASMA2I   ASMA2R
  ASMA2W   ASMA2Z   ASMA26   ASMA7EN  ASMA7UE  ASMA9Z   ASMA92
  

Fix information

• Fixed component name

  HLASM MVS, VM &

• Fixed component ID

  569623400

Applicable component levels

• R160 PSY UI78978

     UP22/01/21 P F201

• R360 PSY UI78977

     UP22/01/20 P 2201

• R689 PSY UI78979

     UP22/01/20 I 1000

Fix is available

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