IOSB Contents ACP-QIO Functions shows the I/O status block (IOSB)
for ACP--QIO functions.
I/O Function Codes lists
the status returns for these functions. (The OpenVMS system messages
documentation provides explanations and suggested user actions for
these returns.)
The file ACP returns a completion status in the first longword
of the IOSB. In an extend operation, the second longword is used
to return the number of blocks allocated to the file. If a contiguous
extend operation (FIB$V_ALCON) fails, the second longword is used
to return the size of the file after
truncation.
Values returned in the IOSB are most useful during operations
in compatibility mode. When executing programs in the native mode,
use the values returned in FIB locations.
Figure 8 IOSB Contents -- ACP-QIO Functions
If an extend operation (including CREATE) was performed, IOSB+4
contains the number of blocks allocated, or the largest available
contiguous space if a contiguous extend operation failed. If a truncate
operation was performed, IOSB+4 contains the number of blocks added
to the file size to reach the next cluster boundary.
HP OpenVMS I/O User's Reference Manual
ACP-QIO Interface
