flags
ctl
count
is the standard CCW flag field with the suppress incorrect
length indication (SLI) bit on.
is a control byte that indicates the starting output display
line. If the high order bit is on, the entire 3270 output
display area is erased before the new data is displayed. A value of X'FF' clears the screen, but writes nothing.
is a two byte field indicating the number of bytes to be
displayed. The maximum number of bytes for the 3278 Bodel 2A is 1440. For other types it is 1760. When the DIAGIOSB is executed with a valid CCW string, a buffer
(whose length is the nuaber of bytes specified by is built in
free storage. The data pointed to by is loaded into the buffer.
Data chaining may be specified in the CCW to link noncontiguous data
areas; however, command chaining is an end of data indication for the
current buffer. Using the starting output line (ctl) and the number of bytes of
output (count), CP checks that the data will fit on the screen. CP then
does the display. A zero condition code indicates the I/O operation
completed successfully; a nonzero condition code indicates an I/O error
occurred. lote: An I/O error occurs when the display screen is placed in BORE status and the PA2 key is pressed to allow screen display.
Execution of DIAGIOSE code X'SC' causes the editing of an error message according to the user's setting of the BBSG function: Rx contains the address of the message to be edited. Ry contains the length of the aessage to be edited. DMKBVC tests the VMMLBVBL field of the V!BLOK and returns to the caller
with Rx and Ry modified as follows: VM!LBVBL Registers on Return VMMCODB I V!MTBXT Rx Ry I 01 I 01 no change no change I 01 I OFF no change 10 (length of I code) I OFF I ON pointer to text length of text I part of message alone I OFF I OFF I/A 0 lote: DIAGNOSE code X'SC' does not write the message; it merely rearranges the starting pointer and length. Par CBS error aessages, a
console write is performed following the DIAGNOSE unless Ry is returned with a value of O. 1-66 IBM VM/310 System Logic and Problem Determination--VoluBe 1

= Determining the !irtual !achine storage Size Execution of DIAGNOSE code X'60' allows a virtual machine to determine its size. On return, the register specified as Rx contains the virtual
machine storage size.
Execution of DIAGNOSE code X'64' controls the linkage of discontiguous
saved segments. The type of linkage that is performed depends upon the
function subcode in the register specified as Ry= Function segment in shared mode Subcode -Foo' X'04' X'08' X'OC' LOIDSYS LOIDSYS PURGESYS FINDSYS Loads a named segment in nonshared mode Releases the named segment from virtual storage
Finds the starting address of the naaed segment The register specified as Rx must contain the address of the name of
the segment. The segment name must be 8 bytes long, left justified, and
padded with trailing blanks. When the LOIDSYS diagnose function is executed, CP finds the system name table entry for the named system and builds the necessary page and swap
tables. Two sets of page and swap tables, one for each processor, are
built for each shared segment in attached processor mode unless the
naaed system was defined as unprotected. CP releases all the virtual
pages of storage that are to contain the named segment and then loads
the segment in those virtual pages. When the LOIDSYS function is
executed, CP expands the virtual machine size dynamically, if necessary. CP dlso expands the segment tables to match any expansion of virtual storage_ When LOADSYS executes successfully, the address of where
segment was loaded is returned in the register specified as
the LOIDSYS function loads a segment in shared mode, instruction and branch tracing if either was active.
the naaed Rx. When it resets
lfter a LOIDSYS function executes, the storage occupied by the naaed segment is addressable by the virtual aachine, even if that storage is
beyond the storage defined for the virtual machine. However, any
storage beyond that defined for the virtual machine and below that
defined for the named segment is not addressable. Figure 15 shows the
virtual storage that is addressable before and after the LOIDSYS function executes. CP Introduction 1-67