April 1, 1981
Comparison of CP and CMS Facilities for Debugging
If vou debuqqing problems while runninq CMS, you can choose the CP or :MS debuqqinq tools. Refer to Fiqure 18 for a comparison of the CP and :MS debugging tools.
r , FI} nction
,-------- , settinq laddl"es::; ,stops. 1------ I D'lm')inq ,contents lof tot he I printel". , I I I Displav in ql the COl- I tents ')f I stOl"aqe I and I cont rol , reqistel"s I at +-.he I I 1-------- IStol"ing- linf')r-m3.­ I t ion. I I I I I , , I I Tracin:l ti:>n. Can set only one address stop at a time. The dump is printed in hexadecimal format
with POCDIC translation. The storage ad­
dress of the first byte of each line is
identified at the left.
The display is typed in hexadecimal format
with EBCDIC translation. The CP command I 1isplays storage keys, floatinq-point regi-I sters and control registers. , The amount of information stored by the CP
command is limited only by the length of +-he input line. The information can be Fullword aligned when stored. CP stores data in floating-point and control reqis­
ters, as well as in qeneral reqisters. CP
stores data in the psw, but not in the CAW or CSW. However, data can be stored in the or CAW by specifying the hardware ad­ dress in the STORE command. Cp t.races: • All interruptions, instructions, and
branches • SVC interruptions • I/O interruptions • Proqram interruptions • External interruptions • Pr-ivileged instructions • user I/O operations • Virtual and real CCW's • All instructions
The CP trace is interactive. You can stop
it and display other fields. I I , , I L ________________ _
, CMS I I :an set up to 16 stopSI at a time. t I , The dump is printed in I decimal format. The I address of the first byte of , each line is identified thel
left. The contents of general , and floating-point reqisters I are printed at the beginninq , of the dump. , t
The display is typed in nex3.- I decimal format. The CMS I mands £g display stoI:"3.qe , keys, floating-point reqistersl or control registers as the CPt command does. I I , , ------t
The :MS command stores up to , 12 bytes of information. :MS , stores data in the , registers but not in the , floating-point or control req-I isters. CMS stores data in the, PSW, CAW, and CSW. I :MS traces all SVC interrup­
tions. CMS displays the
contents of general and
floating-point reqisters
before and after a routine is
called. The parameter list is
recorded befoI:"e a
routine is called. , , , Fiqure 18. Comparison of CP and CMS Facilities for Debugging 222 eMS User's Guide

March 30, 1979
What Your Virtual Machine Storage Looks Like
Figure 19 illustrates a simplified CMS storage map. The portion of
storage that is of most concern to you is the user program area, since
that is where your programs are loaded and executed. The user program area and some of the other areas of storage shown in the figure are
discussed below in general terms= When you issue a LOAD command (for OS or CMS programs) or a FETCH command (for DOS programs), and you do not specify the ORIGIN option,
the first, or only, program you load is loaded at location 1'20000', the teginning of the user program area.
The upper limit, or maximum size, of the user program area is
determined ty the storage size of your virtual machine. You can find
out how large your virtual machine is by using the CP QUERY command:
cp query virtual storage
If you need to increase the size of your virtual machine, then you
must use the CP command DEFINE. For example:
cp define storage 1024k increases the size of your virtual machine to 1024K bytes. If you are
in the eMS when you enter this you receive a
message like: STORAGE = 01024K DMKDSP450W CP ENTERED; DISABLED WAIT PSW 'OC020000 00000000' and you must reload CMS with the IPL command before you can continue. You might need to redefine your virtual machine to a larger size if
you execute a program that issues many requests for free storage, with
the OS GETMAIN or DOS/VS GETVIS macros. CMS allccates this storage from the user program area.
At the top of the user program area are the loader tables, that are
used by the CMS loader to point to programs that have have been loaded. You can increase the size of this area with the CMS SET LDRTBLS command.
If you use the SET LDRTBLS command, you should issue it immediately
after you IPL CMS. The transient program area is used for loading and executing
disk-resident CMS MODULE files that have been created using the ORIGIN TRANS option of the LOAD command, followed by the GENMOD command. For more information on CMS MODULE files and the transient area, see
nExecuting Program Modules" in "Section 13. Programming for the CMS Environment." SHARED AND NONSHARED SYSTEMS The areas in storage labeled in Figure 19 as the CMS nucleus and the
ncss are system programs that are loaded by various types of requests. When you enter the command:
cp ipl CIIS Section 11. How VM/370 Can Help You Debug Your Programs 223