Macro-SVC No. siip-sic51-- ENQ-SVC56 FREEDBUF-SVC51 STIE-SVC60 DETACH-SVC62 CBKPT-SVC63 RDJFCB-SVC64 SYNADAF-SVC68 SYBADRLS-SVC68 BSP-SVC69 TGET/TPUT­ SVC93 TCLEARQ-SVC94 STAI-SVC96 BOTE Except for SDATA, PDATA, and DCB, all options of the SNAP macro are processed normally. SDATA and PDATI are ignored. processing for the DCB option is as
follows. The DBC address specified with SNAP is used
to verify that the file associated with the DCB is If it is not open# control is returned to the
caller with a return code of 4. If the file is open,
then storage is dumped (unless the FCB indicates a DUMMY device type). SNAP always dumps output to the
printer. The dump contains the PSi, the registers,
and the storage specified.
The ENQ routine in CMS is a BOP. to the user.
It returns control
All the options of FREEDBUF are supported. FREEDBUF returns a buffer to the buffer pool assigned to the
specified DCB. are supported except for the
set to ICTL=YES; the PURGE HALT; and the ASYNCH option, STAE creates, overlays, or
All the options of STAE ICTL option, which is
option, which is set to
which is set to NO. cancels a STAB control
is not supported.
block as requested. STAE retry
The DETACH routine in CMS is a NOP. control to the user.
It returns
The CHKPT routine is a NOP. It returns control to the
user.
All the options of RDJFCB are supported. RDJFCB causes a Job File Control Block (JFCB) to be read fro.
a CMS Control Block (C!SCB) into real storage for each
data control block specified. CMSCBs are created by
FILEDEF commands.
All the options of SYNADAF are supported. SYNADAF analyzes an I/O error and creates an error message in a work buffer.
All the options of SYNADRLS are supported. SYNADRLS frees the work area acquired by SYNAD and deletes the work area froa the save area chain.
All the options of BSP are supported. BSP decrements
the item pointer by one block.
TGET and TPUT operate as if EtIT and WAIT were coded.
TGET reads a terminal line. iPUT writes a terminal
line. TCLEARQ in CMS clears the input terminal queue and
returns control to the user. Updates a queue of C!TAIEs each of which defines an
attention exit level.
All the options of NOTE are supported. BOTE returns
the item number of the last blcck read or written. CMS Introduction 2-41

!!acro-SVC !.Q. im'T---- CHECK
DCB BPALI BLKSIZE BUPCB BUFL BUFIO DDNlftE DSOBG EODAD EXLST KEYLEN LIMCT LRECL ftlCRP OPTCD RECFft SYNAD IfCP All the options of POINT are supported. POINT causes
the control program to start processing the next read
or write operation at the specified item number. The
TTR field in the block address is used as an item
number.
All the options of CHECK are supported.
the I/O operation for errors and
conditions.
The following fields of a rCB may be
CHECK tests
exceptional
specified,
relative to the particular access method indicated: BDAM P,D F,D P,D F,D
n (number) n n n
a (address) a a a
n n n n
n n n n
s (symbol) s s s V1 PO PS PS a a a
a a a a
n n
n
n n n R,i R,i R, i, P G,P,L,M A,E,F,R F,', U F,V,U F,V,B,S,A,M,U F,V,B,U,A,M,S a a a a
n n ACCESS ftETHOD SUPPORT The manipulation of data is governed by an access method. To facilitate
the execution of OS Code under CMS, the processing program must see data
as OS would present it. For instance, when the processors expect an
access method to acquire input source cards sequentially, CMS invokes
specially written routines that simulate the as sequential access method
and pass data to the processors in the format that the OS access methods
would have produced. Therefore, data appears in storage as if it had
been manipulated using an OS access method. For example, block
descriptor words (BDi), buffer pool management, and variable records are
updated in storage as if an OS access method had processed the data.
The actual writing to and reading from the I/O device is handled by file management. Note that the character string X'61FFFF61' is
interpreted by CftS as an end of file indicator.
The essential work of the volume table of contents (VTOC) and the
data set control block (DSCB) is done in CMS by a master file directory (ftPD) which updates the disk contents, and a file status table (FSt) (one for each data file). All disks are formatted in physical blocks of 800 bytes. CftS continues to update the OS format, within its own format, on the auxiliary device, for files whose filemode number is 4. That is, the
block and record descriptor words (BDW and RDW) are written along with
the data. If a data set consists of blocked records, the data is
written to, and read from, the I/O device in physical blocks, rather
than logical records. CMS also simulates the specific methods of manipulating data sets. 2-42 IBft 'ft/370 System Logic and program Determination--Voluae 2