How Found
Use the OBTAIN macro or a CVAF macro.
Determining the Type of Data Set: To learn
the type of a data set, test the DS1DSORG field. Except for the DS1DSGU
bit, only one bit should be on. If no bit is on, the data set is
not standard and the system generally treats it like DSORG=PS. The
explanation for all DS1DSORG bits being off might be:
- The user did not specify the DSORG option and no program has written data in the data set.
- The data set was created by a program that used EXCP or EXCPVR.
- The data set was created on another operating system.
- Physical sequential (DSORG=PS). There are three types:
- Large format if the DS1LARGE bit is on.
- Extended format if the DS1STRP bit is on. An indicator in the catalog entry specifies whether it is striped.
- Basic format if neither of the above two bits is on.
- Direct (DSORG=DA).
- Partitioned (DSORG=PO). This can signify one of three types of
data set:
- PDS (partitioned data set) if the DS1PDSE and DS1PDSEX bits are off.
- PDSE (partitioned data set extended) if the DS1PDSE bit is on and DS1PDSEX bit is off.
- HFS (hierarchical file system) if the DS1PDSE and DS1PDSEX bits are on.
- VSAM (AMORG). You can use CSI, catalog search interface, to determine the type of VSAM data set. If it is a linear data set, it might contain a DB2® tablespace or a z/OS file system (zFS) or something else.
Table 1 shows the contents of a format-1
or format-8 DSCB.
The DS1REFD field:
- For a VSAM data set, if the date in the FMT-1 DSCB's DS1REFD field is earlier than the current date, OPEN updates the field with the current date.
- For a multivolume VSAM data set, OPEN updates the DS1REFD field only for the first volume of the data component of the base cluster.
- For a non-VSAM multivolume data set that is not SMS managed, OPEN updates the DS1REFD field on the first volume OPEN selected to use.
- For a non-VSAM multivolume SMS-managed data set that is not extended format, OPEN updates the DS1REFD field on the first volume OPEN selected to use, as well as the first volume of the data set.
- For an extended format single-striped non-VSAM data set, OPEN updates the DS1REFD field on the first volume OPEN selected to use, as well as the first volume of the data set.
- For an extended format multi-striped non-VSAM data set, OPEN updates the DS1REFD fields on all volumes of the data set.
Offset Dec (Hex) | Type or Bit Mask | Length | Name | Description |
---|---|---|---|---|
0(X'0') | Character | 44 | DS1DSNAM | Data set name. |
44(X'2C') | Character | 1 | DS1FMTID | Format Identifier. |
DS1IDC | X'F1'. This is a format-1 DSCB. | |||
DS8IDC | X'F8'. This is a format-8 DSCB. | |||
45(X'2D') | Character | 6 | DS1DSSN | Data set serial number (identifies the first or only volume containing the data set/space). |
51(X'33') | Unsigned | 2 | DS1VOLSQ | Volume sequence number. |
53(X'35') | Character | 3 | DS1CREDT | Creation date ('YDD'), discontinuous binary. Add 1900 and the value in the Y byte to determine the year. For VSAM data sets that are not SMS-managed, the expiration date is in the catalog. |
56(X'38') | Character | 3 | DS1EXPDT | Expiration date ('YDD'), discontinuous binary. Add 1900 and the value in the Y byte to determine the year. |
59(X'3B') | Unsigned | 1 | DS1NOEPV | Number of extents on volume. |
60(X'3C') | Unsigned | 1 | DS1NOBDB | Number of bytes used in last directory block. |
61(X'3D') | Bitstring | 1 | DS1FLAG1 | Flags byte |
1 . . . . . . . | DS1COMPR | Compressible format data set (DS1STRP is also 1). | ||
. 1 . . . . . . | DS1CPOIT | Checkpointed data set. | ||
. . 1 . . . . . | DS1EXPBY | VSE expiration date specified by retention period (not currently used in z/OS) | ||
. . . 1 . . . . | DS1RECAL | Data set recalled. | ||
. . . . 1 . . . | DS1LARGE | Large format data set. | ||
. . . . . 1 . . | DS1ENCRP | Access method encrypted data set. | ||
. . . . . .11 | DS1EATTR | Extended attribute setting as specified on the allocation request.(EATTR=)
|
||
62(X'3E') | Character | 13 | DS1SYSCD | System code. |
75(X'4B') | Character | 3 | DS1REFD | Date last referenced ('YDD' or zero, if not maintained). Add 1900 and the value in the Y byte to determine the year. |
78(X'4E') | Bitstring | 1 | DS1SMSFG | System managed storage indicators. |
1 . . . . . . . | DS1SMSDS | System managed data set. IEHLIST displays this bit as the letter S. |
||
. 1 . . . . . . | DS1SMSUC | Uncataloged system managed data set (the VTOC index is an uncataloged
system managed data set as are all temporary data sets on system managed
volumes). IEHLIST displays this bit as the letter U. |
||
. . 1 . . . . . | DS1REBLK | System determined the block size and data set can be reblocked
(you or the system can reblock the data set). IEHLIST displays this
bit as the letter R. |
||
. . . 1 . . . . | DS1CRSDB | DADSM created original block size and data set has not been
opened for output. IEHLIST displays this bit as the letter B. |
||
. . . . 1 . . . | DS1PDSE | Data set is a PDSE or HFS data set (DS1PDSEX is also 1 for
HFS). IEHLIST displays this bit as the letter Ifor a PDSE. IEHLIST displays a ?when it finds an invalid combination of bits. |
||
. . . . . 1 . . | DS1STRP | Sequential extended-format data set. IEHLIST displays this
bit as the letter E. IEHLIST displays a ?when it finds an invalid combination of bits. |
||
. . . . . . 1 . | DS1PDSEX | HFS data set (DS1PDSE must also be 1) IEHLIST displays this
bit as the letter H. |
||
. . . . . . . 1 | DS1DSAE | Extended attributes exist in the catalog entry. | ||
79(X'4F') | Character | 3 | DS1SCEXT | Secondary space extension. Valid only when DS1EXT is on (see offset 94(X'5E')). |
79(X'4F') | Bitstring | 1 | DS1SCXTF | Secondary space extension flag byte–only one of the first 4 bits is on. |
1 . . . . . . . | DS1SCAVB | If 1, DS1SCXTV is the original block length. If 0, DS1SCXTV is the average record length. | ||
. 1 . . . . . . | DS1SCMB | If 1, DS1SCXTV is in megabytes. | ||
. . 1 . . . . . | DS1SCKB | If 1, DS1SCXTV is in kilobytes. | ||
. . . 1 . . . . | DS1SCUB | If 1, DS1SCXTV is in bytes. | ||
. . . . 1 . . . | DS1SCCP1 | If 1, DS1SCXTV has been compacted by a factor of 256. | ||
. . . . . 1 . . | DS1SCCP2 | If 1, DS1SCXTV has been compacted by a factor of 65,536. | ||
80(X'50') | Unsigned | 2 | DS1SCXTV | Secondary space extension value for average record length or average block length. |
82(X'52') | Bitstring | 2 | DS1DSORG | Data set organization. |
First byte of DS1DSORG | ||||
1000 000x | DS1DSGIS | Indexed sequential organization. | ||
0100 000x | DS1DSGPS | Physical sequential organization. | ||
0010 000x | DS1DSGDA | Direct organization. | ||
0001 000x | DS1DSGCX | BTAM or QTAM line group. | ||
. . . . xx . . | Reserved. | |||
0000 001x | DS1DSGPO | Partitioned organization. | ||
. . . . . . . 1 | DS1DSGU | Unmovable; the data contains location dependent information. | ||
Second byte of DS1DSORG | ||||
100x 00xx | DS1DSGGS | Graphics organization. | ||
010x 00xx | DS1DSGTX | TCAM line group (not supported) | ||
001x 00xx | DS1DSGTQ | TCAM message queue (not supported). | ||
000x 10xx | DS1ACBM | VSAM data set/space. | ||
000x 10xx | DS1ORGAM | VSAM data set/space. | ||
000x 01xx | DS1DSGTR | TCAM 3705 (not supported). | ||
. . . x . . xx | Reserved. | |||
84(X'54') | Character | 1 | DS1RECFM | Record format. |
10 . . . . . . | DS1RECFF | Fixed length. | ||
01 . . . . . . | DS1RECFV | Variable length. | ||
11 . . . . . . | DS1RECFU | Undefined length. | ||
. . 1 . . . . . | DS1RECFT | Track overflow. No longer supported by current hardware. | ||
. . . 1 . . . . | DS1RECFB | Blocked; cannot occur with undefined. | ||
. . . . 1 . . . | DS1RECFS | Fixed length: standard blocks; no truncated blocks or unfilled tracks except possible the last block and track. Variable length: spanned records. | ||
. . . . . 00 . | No control character. | |||
. . . . . 10 . | DS1RECFA | ISO/ANSI control character. | ||
. . . . . 01 . | DS1RECMC | Machine control character. | ||
. . . . . 11 . | Reserved. | |||
. . . . . . . x | Reserved. | |||
85(X'55') | Character | 1 | DS1OPTCD | Option Code. |
BDAM OPTCD field assignments (applies only if DS1DSGDA is on):
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1 . . . . . . . | Write validity check. | |||
. 1 . . . . . . | Track overflow. | |||
. . 1 . . . . . | Extended search. | |||
. . . 1 . . . . | Feedback. | |||
. . . . 1 . . . | Actual addressing. | |||
. . . . . 1 . . | Dynamic buffering. | |||
. . . . . . 1 . | Read exclusive. | |||
. . . . . . . 1 | Relative block addressing. | |||
ISAM OPTCD field assignments (applies only if DS1DSGIS is on):
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1 . . . . . . . | Write validity check. | |||
. 1 . . . . . . | Accumulate track index entry. | |||
. . 1 . . . . . | Master indices. | |||
. . . 1 . . . . | Independent overflow area. | |||
. . . . 1 . . . | Cylinder overflow area. | |||
. . . . . 1 . . | Reserved. | |||
. . . . . . 1 . | Delete option. | |||
. . . . . . . 1 | Reorganization criteria. | |||
BPAM, BSAM, QSAM OPTCD field assignments (applies only if DS1DSGPO or DS1DSGPS is on):
|
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1 . . . . . . . | Write validity check. | |||
. 1 . . . . . . | Allow data check (if on printer). | |||
. . 1 . . . . . | Chained scheduling. | |||
. . . 1 . . . . | VSE/MVS interchange feature on tape. | |||
. . . . 1 . . . | Treat EOF as EOV (tape). | |||
. . . . . 1 . . | Search direct. | |||
. . . . . . 1 . | User label totaling. | |||
. . . . . . . 1 | Each record contains a table reference character. | |||
85(X'55') | Bitstring | 1 | DS1OPTAM | VSAM OPTCD settings. |
VSAM OPTCD field assignments (applies only if DS1ORGAM is on):
|
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1 . . . . . . . | Reserved. | |||
. 1 . . . . . . | DS1OPTBC | Data set is an integrated catalog facility catalog. | ||
. . xx xxxx | Reserved. | |||
86(X'56') | Binary | 2 | DS1BLKL | Block length (Type F unblocked records), or maximum block size (F blocked, U or V records). |
88(X'58') | Binary | 2 | DS1LRECL | Logical record length: Fixed length-record length, Undefined length-zero, Variable unspanned-maximum record length, Variable spanned and < 32757 bytes-maximum record length, Variable spanned and > 32756 bytes-X'8000'. |
90(X'5A') | Binary | 1 | DS1KEYL | Key length ( 0 to 255). |
91(X'5B') | Binary | 2 | DS1RKP | Relative key position. |
93(X'5D') | Character | 1 | DS1DSIND | Data set indicators. |
1 . . . . . . . | DS1IND80 | Last volume containing data in this data set. | ||
. 1 . . . . . . | DS1IND40 | Data set is RACF™, a component of the Security Server for z/OS, defined with a discrete profile. | ||
. . 1 . . . . . | DS1IND20 | Block length is a multiple of 8 bytes. | ||
. . . 1 . . . . | DS1IND10 | Password is required to read or write, or both; see DS1IND04. | ||
. . . . 1 . . . | DS1IND08 | Data set has been modified since last recall. | ||
. . . . . 1 . . | DS1IND04 | If DS1IND10 is 1 and DS1IND04 is 1, password required to write, but not to read. If DS1IND10 is 1 and DS1IND04 is 0, password required both to write and to read. | ||
. . . . . . 1 . | DS1IND02 | Data set opened for other than input since last backup copy made. | ||
DS1DSCHA | Same as DS1IND02. | |||
. . . . . . . 1 | DS1IND01 | Secure checkpoint data set. | ||
DS1CHKPT | Same as DS1IND01. | |||
94(X'5E') | Binary | 4 | DS1SCALO | Secondary allocation space parameters. |
94(X'5E') | Character | 1 | DS1SCAL1 | Flag byte. |
xxxx xxxx | DS1DSPAC | Space request bits, defined as follows: | ||
00 . 0 . . . . | DS1DSABS | Absolute track request. | ||
00 . 1 . . . . | DS1EXT | Extension to secondary space exists (see DS1SCEXT at offset 79 (X'4F')). | ||
11 . . . . . . | DS1CYL | Cylinder request. | ||
10 . . . . . . | DS1TRK | Track request. | ||
01 . . . . . x | DS1AVR | Average block length request. | ||
01 . . . . . 1 | DS1AVRND | Average block and round request. | ||
. . 1 . . . . . | DS1MSGP | Mass storage vol group (MSVGP - no longer supported). | ||
. . . . 1 . . . | DS1CONTG | Contiguous request. | ||
. . . . . 1 . . | DS1MXIG | MXIG request. | ||
. . . . . . 1 . | DS1ALX | ALX request. | ||
. . . . . . . 1 | - | Round request. | ||
95(X'5F') | Binary | 3 | DS1SCAL3 | Secondary allocation quantity. |
98(X'62') | Binary | 3 | DS1LSTAR | Last used track and block on track (TTR). Not defined for VSAM, PDSE, HFS and direct (BDAM). See bit DS1LARGE at +61 and byte DS1TTTHI at +104. |
101(X'65') | Binary | 2 | DS1TRBAL | If not extended format, this is the value from TRKCALC indicating space remaining on last track used. For extended format data sets this is the high order two bytes (TT) of the four-byte last used track number. See DS1LSTAR. Zero for VSAM, PDSE, and HFS. |
103(X'67') | Character | 1 | Reserved. | |
104(X'68') | Character | 1 | DS1TTTHI | High order byte of track number in DS1LSTAR. Valid if DS1Large is on. |
105(X'69') | Character | 30 | DS1EXNTS | Three extent fields. |
105(X'69') | Character | 10 | DS1EXT1 | First extent description. |
Character | 1 | Extent type indicator. | ||
X'81' | Extent on cylinder boundaries. | |||
X'80' | Extent described is sharing cylinder (no longer supported). | |||
X'40' | First extent describes the user labels and is not counted in DS1NOEPV. | |||
X'04' | Index area extent (ISAM). | |||
X'02' | Overflow area extent (ISAM). | |||
X'01' | User's data block extent, or a prime area extent (ISAM). | |||
X'00' | This is not an extent. | |||
1 | Extent sequence number. | |||
4 | Lower limit (CCHH). These are the bit definitions:
|
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4 | Upper limit (CCHH). Same format as the lower limit. | |||
115(X'73') | Character | 10 | DS1EXT2 | Second extent description. |
125(X'7D') | Character | 10 | DS1EXT3 | Third extent description. |
135(X'87') | Character | 5 | DS1PTRDS | In a format-1 DSCB this can be a pointer (CCHHR) to a format-2 or format-3 DSCB or be zero. In a format-8 DSCB this always is the CCHHR of a format-9 DSCB. |
140(X'8C') | Character | DS1END | - |