disk; if it is, another check determines if the accessed disk replaces another disk to issue an information message tc that effect. Another
check determines if you specified any options or fileid and, if you did,
a warning message appears On the terminal. Control now returns to the
calling routine. DMSFLD gets control first when you issue a FILEDEF command. DMSFLD adds, changes, or deletes a FILEDEF control
block and returns control to the calling routine. LISTDS COMMAND FLOW: The module DMSLDS gets control first when you Invoke the-IISTDS-comaand. DMSLDS verifies parameter list validity and
calls module DESLAD to get the active disk tatle associated with the
specified mode. DMSLDS reads all format 1 DSCB and if you specified the PBS option and the data set is partitioned, DMSLDS calls DMSRCS (ROSFIND) to get the members of the data set. After displaying the DSCB (or DSCB) on you console, DMSLDS returns to the calling routine. I1Q!: The module DMSMVE gets control first when you
issue a CMS MOVEFILE command. DMSMVE calls DMSFLD to get an input and
output CMSCB and, if the input DMSCB is for a disk file, DMSftVE calls DMSSTT to verify the existence of the input file and get default DCB parameters in absence of CMSCB DCB parameters. DMSMVE uses OS OPEN, FIND, GET, PUT, and CLOSE macros to move data from the input file to the
output file. After moving the specified data, control returns to the
calling routine. 2QER! £QMMA!Q I1Q!: The module DMSQRY gets control first when you invoke
the QUERY command. DMSQRY verifies parameter list validity and calls DMSLAD to get the active disk table associated with the specified mode. DMSQRY displays all the information that you requested on your console. When DMSQRY finishes, control returns to the calling routine. FLQ!: The module DMSARE gets control first when you
invoke the RELEASE command. DMSARE verifies parameter list validity and
checks to determine if the disk you want to release is accessed. If the
disk you want to release is currently active, DMSARE calls D8SALU to
clear all pertinent information associated with the active disk. DMSALU first checks the active disk table for any existing CMS tables kept in
free storage. If the disk you want to release is an OS disk, DMSALU does not find any tables associated with a CMS disk. If the disk is an OS disk, D5SALU releases the os PST blocks (if any) and clears any OS PST pointers in the OS file control blocks. DMSALU then clears the
active disk table and returns to DMSARE. DMSIRE then clears the device
table address for the specified disk and returns to the calling routine. STATE fLO!: The module DMSSTT gets control first when you invoke
the STATE command. DMSSTT verifies the parameter list validity and
calls module DMSLAD to get the active disk table associated with the
specified mode. Upon return from DMSLAD, DMSSTT calls DMSLFS to find
the file status table (FST) associated with the file you specified. Once DMSLFS finds the associated FST, it checks to determine if the file
resides on an OS disk. If it does, DMSLFS calls DMSROS (ROSSTT) to read
the extents of the data set. Upon return from D"SROS, DMSLFS returns to DMSSTT. DMSSTT then copies the FST (or OS FST) to the FST copy in
statefst and returns to the calling routine. DMSACC MODULE: Once DMSACC determines that the disk you want to access Is-an-oS-disk, it bypasses the routines that perfor. LOGIN UFD and LOGIN ERASE. CMS Method of Operation and Program Organization 2-131

If the disk you want to access replaces an OS disk, message DMSACC724I appears at your terminal.
If you specified any options or fileid in the ACCESS command to an OS disk, a warning message, DMSACC230W, appears to notify you that such
options or fileid were ignored. DMSACC returns to the calling routine
with a warning code of 4. DMSACF verifies that the disk you want to access is an OS disk and, if it is, exits immediately. DMSACM MODULE: DMSACM saves the disk label and VTOC address in the ADT block- Ii-the disk is an as disk. DMSACM checks to determine if a
previous access to an os disk leaded DMSROS. If not, DMSACM calls DMSSTT to verify that DMSROS text exists. Upon successful return from
STATE, DMSACM loads DMSROS text into the high storage area with the same
protect key and calls the OS access routine (ROSACC) of DMSROS to read
the format 4 DSCB of the disk. Upon successful return from DMSROS, control returns to the calling routine. Any other errors are treated as
general logen errors. DMSALU MODULE: If the disk is an os disk, DMSFRET returns the as FST blocks clf-any) to free storage. DMSALU clears the OS FST pointer in
all active as file control blocks, decrements the DMSROS usage count
and, if the usage count is zero, clears the address of DMSROS in the
nucleus area. DMSALU also calls DMSFRET to returns to free storage the
area which DMSROS occupies. DMSARE MODULE: DMSARE ensures that the disk you want to relase is an OS aisk:- -DMSliE calls DMSALU to release alIOS FST blocks and, if
necessary, to free the DMSROS occupies. UFon return from DMSALU, DMSARE clears the common CMS and OS active disk table. • DSN If you specify the parameter DSN as a question mark (1) ,
FILEDEF displays the message DMSFLD220R to request you to type in an OS data set name with the format Q1.Q2.QN. Ql, Q2, and QN are the
qualifiers of an OS data set name. If you specify the parameter DSN as Ql.Q2.QN, FILEDEF assumes that Ql, Q2, and QN are the qualifiers
of an OS data set name, and stores the qualifiers with the format Ql.Q2.QN in a free storage block and chains the block to the FCB. • CONCAT -- If you specify the CONCAT option, FILEDEF assumes that the
specified FILEDEF is unique unless a filedef is outstanding with a
matching ddna.e, filename, and filetype. This allows you to specify
more than one FILEDEF for a particular ddna.e. The CONCAT option
also sets the FCBCATML bit in the FCB to allow the OS simulation
routine to know the FCB is for a concatenated MACLI8. • MEMBER -- If you specify the member option, filedef stores the member
name in FCBMEMBR in the FCB to indicate that the OS simulation
routine should set the read/write pointer to point to the specified BPAM file member when OPEN occurs. DMSLDS saves the return register, sets itself with the
nucleus protection key, clears the dsname key, and initializes its
internal flag. DMSLDS verifies parameter list validity. The data set name must not
exceed 44 characters, and the disk mode (the last parameter before the
options) must be valid. DMSLDS joins the quailifiers with dots (.) to
form valid data set names. If you specify the data set name as a
question mark (?), DMSLDS prompts you to enter the dsname in exactly the
same form as the dsname which apFears on the disk.
2-132 IBM VM/370 System Logic and Program Determination--Volume 2