Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
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CHECKPOINTMANY Procedure
(Superseded by CHECKPOINTMANYX Procedure )
For example:
•
Maximum checkpoint size
The largest stack area or data item that can be checkpointed is 32,500 bytes.
Additionally, the sum total of the sizes of the stack area and each checkpoint item,
plus an allowance of 20 bytes for each item, should not exceed 32,500 bytes. An
item in this context means either a data item (of user declared size) or a file
synchronization block of varying sizes.
•
The CHECKPOINTMANY procedure allows checkpointing of both the process’s
data stack and any number of blocks.
•
Identification of the backup process
The system identifies the process to be affected by the CHECKPOINTMANY
operation from the process’s mom field in the process control block (PCB). For
named process pairs, this field is automatically set up during the creation of a
backup process.
•
Illegal parameter
If an attempt is made to checkpoint the data area used by CHECKPOINTMANY for
system-oriented stack maintenance, it returns an “illegal parameter” error (that is,
status.<0:7> = 3).
Figure 3-1. Illegal Parameter Location
If status.<0:7> = 3 then status.<8:15>:
Error is in:
This descriptors pair is a
file sync block item
This descriptors pair is a
data block
Stack base
Count
- 1
filenum
block address
block length
VST005.VSD
Error is (for example):
Invalid address
Bounds of list in error
Checkpoint too large
GETSYNCINFO failed or bad
file number
Bounds error, checkpoint too large
Does not occur
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