SXEQ Back to Index page
 
Prolog 
Control Block Contents 
   SXEQ DSECT
   SXEWK DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.

 
  SXEQ Control Block Content Top of page
 

 SXEQ DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure SXEQ Memory Extension Work Area 0000 0 Signed 8 SXEQsize - Size of 1 set, bytes 0008 8 Signed 8 SXEQstill - Count of sets still on the chain. 0010 16 Bitstring 1 SXEQflag - Flags for this allocation .1.. .... SXEQcntg X'40' SXEQcntg - Total must be contiguous ..1. .... SXEQnoCLR X'20' SXEQnoCLR - Only if second level - Avoid TB or PFMF Clear ...1 .... SXEQnoKEY X'10' SXEQnoKEY - Only if second level - Avoid SSKE or PFMF Key 0011 17 Bitstring 1 * (3) - Reserved 0014 20 Signed 4 * - Reserved 0018 24 Signed 8 SXEQneedO - Count of sets that were originally/actually needed. 0020 32 Address 8 SXEQhead - Pointer to the first entry in a queue of frame sets. Points to the lowest frame in the frame set. 0028 40 Signed 8 SXEQneedN - Count of sets that are still needed. 0030 48 Address 8 SXEQtail - Last frame set, so that we can append to the end 0038 56 Signed 8 SXEQneedC - Count of frame sets that were consumed. 00000040 SXEQLen *-SXEQ
 SXEWK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure SXEWK Memory Extension Work Area Start and end of the real memory that will be attached and assigned by SERVC hardware requests. 0000 0 Address 8 SXEHDST Memory extension start address 0008 8 Address 8 SXEHDSTF FRMTE address for SXEHDST 0010 16 Signed 8 SXEHDSAI Address-incr for SXEHDST 0018 24 Signed 8 * Reserved for IBM use 0020 32 Address 8 SXEHDND A(Memory extension last byte) 0028 40 Address 8 SXEHDNDF FRMTE address for SXEHDND 0030 48 Signed 8 SXEHDNAI Address-incr for SXEHDND 0038 56 Signed 8 * Reserved for IBM use Description of the extension that CP will use. 0040 64 Address 8 SXESTART Memory extension start address 0048 72 Address 8 SXEnTest Address of next frame to test 0050 80 Address 8 SXEEND Memory extension last address 0058 88 Signed 8 * Reserved for IBM use The size by which SXS addressability will be increased. 0060 96 Address 8 SXESXSST SXS growth start address. Because real memory B2G and Host Logical Addressability B2G march together (all because of the use of EDAT-1 for SXSTB) it is expected that the contents of SXESXSST will equal SXEHDST. 0068 104 Signed 8 SXESXSSZ SXS growth in bytes. This will be zero if SYSSXSSZ is already at maximum. 0070 112 Signed 8 * Reserved for IBM use 0078 120 Signed 8 * Reserved for IBM use The pretend ASCE when the DAT structures to be added are being built. 0080 128 Address 8 SXEASCE Pretend ASCE when building DAT The SXEQ blocks for allocating memory and supporting control structures during system initialization. 0090 144 Bitstring 64 SXEcntg SXEQ for SXEQcntg requests 000000D0 SXEfrst * * Define SXEQs for Frame Sets of different sizes. 00D0 208 Bitstring 64 SXEGQ SXEQ for 2G Frame Set 0110 272 Bitstring 64 SXEMQ SXEQ for 1M Frame Set 0150 336 Bitstring 64 SXE4Q SXEQ for 16K Frame Set 0190 400 Bitstring 64 SXE1Q SXEQ for 4K Frame Set * Define SXElast beyond the last SXEQ DSECT defined. 000001D0 SXElast * 01D0 464 Address 4 * In the position of SXEQsize and all zeros to indicate the end of SXEQs When a calculation is performed in order to determine the requirements for frame sets of each size, the calculations start at the ASCE level and drill through all levels of the DAT structure. A distinction is made for the reason for the frame sets. For example, to calculate the number of frame sets for some FRMTB addressability, we would include the number of 16K (AKA 4F) RTT Region First Tables 16K (AKA 4F) RST Region Second Tables 16K (AKA 4F) RTT Region Third Tables 16K (AKA 4F) ST Segment Tables 4K (AKA 1F) PT Page Tables 4K (AKA 1F) BF Backing Frames Following each such calculation, the counts for each frame set size and its usage are accumulated in a final count array. If a prior calculation had already included calculations that would be for the same pieces, say the same Region First Table, then that calculation's count is cleared before the accumulating so that double counting is not performed. 01D8 472 Dbl-Word 8 GFn (0) Alignment 01D8 472 Signed 8 GFn1Fp 1F frame set for PT 01E0 480 Signed 8 GFn4Fs 4F frame set for ST 01E8 488 Signed 8 GFn4Fr3 4F frame set for RTT 01F0 496 Signed 8 GFn4Fr2 4F frame set for RST 01F8 504 Signed 8 GFn4Fr1 4F frame set for RFT 0GFn4Fr1 GFn4Fr GFn4Fs GFn4Fr When we're not exactly sure how a 4F frame set will be used, stick the count in the ST counter GFn4Fs 0200 512 Signed 8 GFn1Fb 1F frame set for backing 0208 520 Signed 8 GFn1Mb 1M frame set for backing 0210 528 Signed 8 GFn2Gb 2G frame set for backing 00000040 GFnLen (*-GFn+7)/8*8 Length of counters 00000043 SXESZD (*-SXEWK+7)/8 SXEWK size in dwords
 
 
  SXEQ Storage Layout Top of page
 
          
*** SXEQ - Memory Extension Work Area
*
*     +-------------------------------------------------------+
*   0 |                       SXEQSIZE                        |
*     +-------------------------------------------------------+
*   8 |                      SXEQSTILL                        |
*     +------+--------------------+---------------------------+
*  10 |:QFLAG|////////////////////|///////////////////////////|
*     +------+--------------------+---------------------------+
*  18 |                      SXEQNEEDO                        |
*     +-------------------------------------------------------+
*  20 |                       SXEQHEAD                        |
*     +-------------------------------------------------------+
*  28 |                      SXEQNEEDN                        |
*     +-------------------------------------------------------+
*  30 |                       SXEQTAIL                        |
*     +-------------------------------------------------------+
*  38 |                      SXEQNEEDC                        |
*     +-------------------------------------------------------+
*  40
*
*** SXEQ - Memory Extension Work Area
          
*** SXEWK - Memory Extension Work Area
*
*     +-------------------------------------------------------+
*   0 |                       SXEHDST                         |
*     +-------------------------------------------------------+
*   8 |                       SXEHDSTF                        |
*     +-------------------------------------------------------+
*  10 |                       SXEHDSAI                        |
*     +-------------------------------------------------------+
*  18 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  20 |                       SXEHDND                         |
*     +-------------------------------------------------------+
*  28 |                       SXEHDNDF                        |
*     +-------------------------------------------------------+
*  30 |                       SXEHDNAI                        |
*     +-------------------------------------------------------+
*  38 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  40 |                       SXESTART                        |
*     +-------------------------------------------------------+
*  48 |                       SXENTEST                        |
*     +-------------------------------------------------------+
*  50 |                        SXEEND                         |
*     +-------------------------------------------------------+
*  58 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  60 |                       SXESXSST                        |
*     +-------------------------------------------------------+
*  68 |                       SXESXSSZ                        |
*     +-------------------------------------------------------+
*  70 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  78 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  80 |                       SXEASCE                         |
*     +-------------------------------------------------------+
*  88 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  90 |                                                       |
*     =                       SXECNTG                         =
*     |                                                       |
*     +-------------------------------------------------------+
*  D0 |                                                       |
*     =                        SXEGQ                          =
*     |                                                       |
*     +-------------------------------------------------------+
* 110 |                                                       |
*     =                        SXEMQ                          =
*     |                                                       |
*     +-------------------------------------------------------+
* 150 |                                                       |
*     =                        SXE4Q                          =
*     |                                                       |
*     +-------------------------------------------------------+
* 190 |                                                       |
*     =                        SXE1Q                          =
*     |                                                       |
*     +---------------------------+---------------------------+
* 1D0 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
* 1D8 |                        GFN1FP                         |
*     +-------------------------------------------------------+
* 1E0 |                        GFN4FS                         |
*     +-------------------------------------------------------+
* 1E8 |                       GFN4FR3                         |
*     +-------------------------------------------------------+
* 1F0 |                       GFN4FR2                         |
*     +-------------------------------------------------------+
* 1F8 |                       GFN4FR1                         |
*     +-------------------------------------------------------+
* 200 |                        GFN1FB                         |
*     +-------------------------------------------------------+
* 208 |                        GFN1MB                         |
*     +-------------------------------------------------------+
* 210 |                        GFN2GB                         |
*     +-------------------------------------------------------+
* 218
*
*** SXEWK - Memory Extension Work Area
 
 
  SXEQ Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
GFn            01D8
GFnLen         0210 00000040
GFn1Fb         0200
GFn1Fp         01D8
GFn1Mb         0208
GFn2Gb         0210
GFn4Fr         01F8 0GFn4Fr1
GFn4Fr1        01F8
GFn4Fr2        01F0
GFn4Fr3        01E8
GFn4Fs         01E0
SXEcntg        0090
SXEfrst        0090 000000D0
SXElast        0190 000001D0
SXEnTest       0048
SXEASCE        0080
SXEEND         0050
SXEGQ          00D0
SXEHDNAI       0030
SXEHDND        0020
SXEHDNDF       0028
SXEHDSAI       0010
SXEHDST        0000
SXEHDSTF       0008
SXEMQ          0110
SXEQcntg       0010 40
SXEQflag       0010
SXEQhead       0020
SXEQneedC      0038
SXEQneedN      0028
SXEQneedO      0018
SXEQnoCLR      0010 20
SXEQnoKEY      0010 10
SXEQsize       0000
SXEQstill      0008
SXEQtail       0030
SXEQLen        0038 00000040
SXESTART       0040
SXESXSST       0060
SXESXSSZ       0068
SXESZD         0210 00000043
SXE1Q          0190
SXE4Q          0150
 
This information is based on z/VM 7.5.0 Last updated on 22 Jun 2026 at 11:16:06 EDT.
Copyright IBM Corporation, 1990, 2026