INITIALIZES STORAGE CONTENTS AND SYSTEM TABLES DMSINS ---Saves the address of this virtual machine in NUCON. Locates and returns the address of the ADT for this virtual machine. DMSFRE free storage to be used during initialization. DMSFRE -- Allocates all low free storage so that the system status table (SSTAT) will be built in high free storage. DMSACM ---aeids the S-disk ADT entry and builds the SSTAT. DMSFRE --Releases the low free storage allocated above (to force SST.AT into
high storage) so that it can be used again. DMSINS ---Stores the address of SSTAT into ASSTAT and ADTFDA in NUCON. Sorts the entries in the PROCESSES IPL COMMAND LINE PARAMETERS DMSINS -- Checks for parameters BATCH, and SEG=, or AUTOCR. If BATCH is
specified, DMSINS sets the flag BATFLAGS. If SEG= is specified, DMSINS loops through again to read the segment name. At this point,
all the parameters on the com.and line have been scanned.
If SEG= is specifiad, the DIAGNOSE 64 FINtSYS function is issued
to determine whether the segment specified on the command line
exists. If it does, the DCSSIVAL flag is temForarily set.
If AUTOCR is specified, a local flag is set so that the subsequent
console read aay be bypassed and the null line input simulated. This
action causes a PROFILE EXEC to be executed. Issues DIAGNOSE 24 to obtain the device type of the console. DMSCWR ---WrItes the system id message to the console. DMSCRD --Reads the IPL command line from the console. Puts the IPL command line in PLIST format. DMSINS ----If-the FINDSYS DIAGNOSE validated the segment name specified on the IPL command line, DMSINS issues a DIAGNOSE 64 SAVESYS function for
that segment.
2-58 IBM VM/370 System Logic and Program Determination--Volume 2

DMSINS ---Clears DCSSAiAL and ensures that all the parameters on the co •• and
line are valid; branches back to label INITLOOP to reprocess for the
segment just saved. If BATCH is specified, sets BATFLAGS and BATFLAG2 in NUCON. Saves the name of the saved system in SYSNAME in NUCON. Issues ACCESS 195 A to access the batch virtual machine A-disk. DMSI!2 Issues DIAGNOSE 60 to get the size of the virtual machine; sets up
enough storage for this virtual DMSINS ---rl-the DCSSAiAL flag is set, sees if the size of the CMSSEG segment
overlaps the size of the virtual machine. If this is the case, DMSINS sets the flag DCSSOiLP and continues the initialization
procedure for a CMS virtual machine running without the use of the CMSSEG segment, that is, performs time-of-day processing and OS initialization.
If the CMSSEG segment can be used, DMSINS issues the DIAGNOSE 64 LOADSYS function as the final check to see if the segment is usable.
If the segaent is loaded successfully, it can be used whenever one of
the functions contained in it is requested. Because it is not
required immediately, DMSINS issues the DIAGNOSE 64 PURGESYS function
to purge the segment. If the segment cannot be successfully loaded, DMSINS turns off the DCSSAiAL flag. INITIALIZE OS SiC-HANDLING WITHOUT THE USE OF THE CMSSEG SEGMENT DMSINS ---Checks for the availability of CMSSEG. DMSSTT ---FInds and returns the address of DMSSiT, the CMS as SVC-handler. Acquires enough free storage to contain DMSSVT. DMSLOA ---roads DMSSVT. Sets the flag DCSSVTLD. DMSINS ---rf-the BATCH virtual machine is not being loaded, determines whether
there is a PROFILE EXEC or a first command line to be handled. If
so, issues SiC 202's to process these commands and passes control to DMSINT, the CMS console manager. If the BATCH virtual machine is being
accesses the D-disk and passes control
manager.
initial program
to DMSINT, the
loaded,
console CMS Method of Operation and Program Organization 2-59