OPEN and CLOSE
This release of the Tachyon Operating System has the following limitations:
- OPEN recognizes the DCB exit list (EXLST) entry for the DCB OPEN exit.
RDJFCB recognizes the JFCB and ARL entries.
All other EXLST entries are ignored.
- Files are not automatically closed at task termination. Any data in
buffers when a program ends will not be written.
- The FREE=CLOSE DD parameter and the
FREE option on the CLOSE macro are ignored and the data set is not deallocated.
BSAM and QSAM
The Tachyon Operating System supports the BSAM and QSAM access methods
for sequential, SYSIN, SYSOUT,
DUMMY, UNIX files and
simulated partitioned data set
members and directories. Most of BSAM and QSAM is supported, with the following
- There is no support for any device other than DASD, so device-specific
services for tape or 3800 printers are not supported.
- There is no support for subsystem data sets other than SYSIN and SYSOUT.
- The OPEN mode INOUT is processed as INPUT.
- User totaling, user labels and QSAM parallel access are not supported.
- Because data sets are stored in workstation files and not on devices
with physical blocks, the NOTE and POINT services return a relative byte
number for FILEDATA=TEXT and RECFM=U, V, VB, VS and VBS data sets. This limits the
use of the NOTE and POINT services on these data sets to the first 16 megabytes.
- Spanned records are not supported by QSAM.
- Concatenated sequential data sets are supported, but the DCBs end-of-data
(EODAD) routine is entered upon encountering end-of-file on the first data
set in a concatenation.
The Tachyon Operating System supports the BDAM access method to access
sequential files with fixed-length, unkeyed records
that were previously loaded using BSAM or QSAM.
The CHECK, CLOSE, OPEN, READ and WRITE services are supported for a BDAM DCB.
Requests for CHECK are ignored because all I/O is marked as completed
after a READ or WRITE request, allowing WAIT to be used for the DECB.
The BDAM DCB must have MACRF of RI, RIC, WI, WIC, (RI,WI) or (RIC,WIC).
MACRF codes A, K, S and X are not supported nor are OPTCD=E and LIMCT.
Only READ DI, READ DIF, WRITE DI and WRITE DIF are supported.
The FREEDBUF and RELEX services are not supported.
The Tachyon Operating System supports the BPAM
access method to access simulated partitioned data sets
in input mode. The BLDL, CHECK, CLOSE, DEBCHK, FIND, LINK(X), LOAD, NOTE,
OPEN, POINT, READ, RDJFCB and XCTL(X) services are supported for a BPAM
DCB. The limitations on NOTE and POINT for BSAM also apply to BPAM. TTRs
are defined similarly to the way they are in z/OSs PDSE support.
The Tachyon Operating System supports
the VSAM access method to access VSAM files in input mode.
The OPEN and CLOSE services are supported for VSAM ACBs.
The CHECK, ENDREQ, GET and POINT services are supported for VSAM RPLs.
The BLDVRP and DLVRP services are ignored.
The GENCB, MODCB, SHOWCB and TESTCB services are supported for VSAM control blocks.
Most of VSAM for input is supported, with the following limitations:
- Because the number of buffers and strings cannot be set in the
AMP parameter of the DD statement and are not
supported for VSAM file definition, the ACB
is the only place where the number of buffers and strings can be set.
The Tachyon Operating System does not support the System Managed Buffers
facility of DFSMS.
The Tachyon Operating System also does not support dynamic string
addition, so the STRNO field of the ACB must be large enough for
all concurrent requests.
- If MAREA and MLEN are specified in the VSAM ACB, the message
area will be cleared but no messages will be placed in the message
area if the OPEN or CLOSE fails.
- Because this release of the Tachyon Operating System does not
support output and update access and alternate indexes, the
MACRF=(OUT) and MACRF=(RST) options are not allowed and the VSAM
file must contain records loaded by the tosvsam utility.
Also the BSTRNO field and the MACRF=(NRM|AIX), MACRF=(DDN|DSN)
and MACRF=(NIS|SIS) options are ignored.
- This release of the Tachyon Operating System does not support
Local Shared Resources, but it will ignore the MACRF=(LSR), MACRF=(DFR|NDF)
and MACRF=(LEW|NLW) options and the SHRPOOL field to allow programs using LSR to run.
Global Shared Resources and Record Level Sharing are not supported,
so MACRF=(GSR) and MACRF=(RLS) are not allowed.
- The OPEN service completely ignores any bits set in the ACBINFLG
field as well as the MACRF=(CFX|NFX) option.
- The following VSAM services are not supported: DIV (Data In Virtual),
Media Manager, catalog services (SVC 26) and SHOWCAT.
- VSAM requests support the EODAD and LERAD exits unless the ,L
option is specified for the exit.
All other EXLST entries are ignored.
Frames No Frames Previous Next Contents
Introduction Setup Programs Files Running Testing
Compatibility Customization Messages Codes
© Copyright 1998-2006, Tachyon
Last modified on January 2, 2006