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Hex Dec Type/Val Lng Label (dup) Comments
---- ---- --------- ---- -------------- --------
0000 0 Structure STD Architected version of the ESA/390
ESA/390 mode STD - 4 bytes, 32 bits
0000 0 Signed 4 STDES (0) Entire STD
.... .... STDSWEM X'80000000' STDSWEM Isolate
space-switch-event bit
000STDES STDSTOM X'7FFFF000' STDSTOM Isolate
segment-table origin
000STDES STDPSM X'00000100' STDPSM Isolate
private-space bit
1... .... STDSAEM X'00000080' STDSAEM Isolate
storage-alteration-event bit.
.111 1111 STDSTLM X'0000007F' STDSTLM Isolate
segment-table length
.1.. .... STDSTUNT 64 STDSTUNT Number of bytes in a
"segment- table unit", the number
of bytes in the smallest
variation of the size of a
segment table.
.... ...1 STDSTL01 X'01' STDSTL01 2 64-byte blocks
(to address 32M)
..11 1111 STDSTL3F X'3F' STDSTL3F 64 64-byte blocks
(to address 1024M).
.1.. .... STDSTL40 X'40' STDSTL40 65 64-byte blocks
(to address 1040M), also, the
number of 64-byte blocks in one
4K page of segment table entries.
.111 1111 STDSTL7F X'7F' STDSTL7F 128 64-byte blocks
(to address 2048M).
.... .11. STDSTUNS 6 STDSTUNS Number of bits to
shift left in order to multiply
by STDSTUNT. Also, number of bits
to shift to convert between STE
offset and corresponding STL
value.
...1 1... STDSXSTL 20+4 STDSXSTL Bits to shift to
convert between an isolated
segment index and the
corresponding segment- table
length. Also used to convert
between STL units and addressable
bytes.
...1 .1.1 STDSXDWS STDSXSTL-3 STDSXDWS Bits to shift
to convert between an isolated
segment index (or number of
addressable bytes) and
doublewords of segment table
space required.
.... ..11 STDDWSTL 3 STDDWSTL Bits to shift to
convert between STL units and
segment table length in
doublewords.
.... .11. STDBYSTL 6 STDBYSTL Bits to shift to
convert between STL units and
segment table length in bytes.
...1 ..1. STDSXDSP 20-2 STDSXDSP Bits to shift right
an isolated segment index to
obtain the displacement into the
segment table of the applicable
STE.
0000 0 Bitstring 1 STD0 STD, byte 0
1... .... STDSWE X'80' STDSWE Space-switch event
bit. When set, space-switch event
program interruptions are
recognized when space switches
occur.
0001 1 Bitstring 1 STD1 STD, byte 1
0002 2 Bitstring 1 STD2 STD, byte 2
.... ..1. STDSSGRP X'02' STDSSGRP Subspace-Group
bit. When set, indicates that the
address space specified by the
STD is part of a subspace group.
.... ...1 STDPRIVS X'01' STDPRIVS Private-space bit.
When set, prefixing, low-address
protection, and fetch- protection
override to not apply to DAT
references.
0003 3 Bitstring 1 STD3 STD, byte 3
1... .... STDSAE X'80' STDSAE
Storage-alteration-event bit.
When set, storage-alteration PER
events in this address space are
enabled via the
storage-alteration-space control
bit of CR9.
00000004 STDSLEN *-STDES Length in bytes of a STD.
00000001 STDSSIZE (STDSLEN+7)/8 Size in doublewords
of a STD.
The following maps the segment-table designation in the
System/370 architecture.
.... .... STD3STLM X'FF000000' Isolate segment-table
length
00FFFFC0 STD3STOM X'00FFFFC0' Isolate segment-table
origin
.... ...1 STD3SWEM X'00000001' Isolate
space-switch-event bit
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