FORTRAN Reference Manual

Statements
FORTRAN Reference Manual—528615-001
7-16
CHECKPOINT Statement
CPLIST = cplist
is an array that contains a checkpoint list constructed by the Saved Message
Utility procedures. You can provide any number of CPLIST specifiers in one
CHECKPOINT statement. See Considerations.
data
is a variable name, array name, array element name, RECORD name, or common
block name that specifies a data item whose value is to be checkpointed by
CHECKPOINT. See Considerations.
Considerations
•
If you omit the UNIT keyword from the unit specifier, unit must be the first item in
the list.
•
If the data item is the name of a common block, you must enclose it in slashes; for
example:
CHECKPOINT (10, ERR=100) /accounts/
•
You can identify files to be checkpointed either by their FORTRAN unit numbers or
by their Guardian file numbers.
•
You must explicitly specify variables, arrays, and RECORDS to be checkpointed in
the data list:
°
If they are in common blocks
°
If they are local data named in SAVE or DATA statements
°
If you specify STACK = 'NO'
Local data not named in SAVE or DATA statements is checkpointed automatically if
STACK = 'YES' is specified or assumed.
•
The data list can include data items with extended addresses. However, the total
size of a checkpoint message cannot exceed 32,767 16-bit words.
•
STACK specifier.
If stack has the value 'YES' (the default value), FORTRAN checkpoints the
memory stack from the initial L register setting to the current S register setting (top
of stack), the corresponding portion of the extended memory stack (if any), the
entities specified in the data list, and all units specified in UNIT specifiers; this
establishes a takeover point for the backup process.
If stack has the value 'NO', FORTRAN checkpoints the entities specified in the
data list and the UNIT= specifiers but does not checkpoint the memory stack and
does not establish a takeover point. If a failure occurs, the backup uses the
takeover point established by the most recent CHECKPOINT statement that
specified or defaulted to a 'YES' stack option. This form is useful if you have to