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Read Modified channel program z/OS Communications Server: SNA Diagnosis Vol 1, Techniques and Procedures GC27-3667-00 |
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The following table shows how CCWs are used in a Read Modified channel program.
1 The number of bytes transmitted in the previous
Read Modified CCW is stored in the LDNRMLEN field in the LDNCB. For
this Read Modified, enough buffers are allocated to hold LDNRMLEN
bytes of data. If this is not enough buffers for the device to send
all of the pending data, the channel program will end on the Read
Skip CCW. The Read Skip CCW reads all of the pending data but does
not transmit any of it. The new length is stored in LDNRMLEN. (The
length is computed by subtracting the residual byte count in the CSW
from X'7FFF'.) Then the channel program is executed again
with one more buffer than necessary allocated to read and transmit
all of the pending data.
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Copyright IBM Corporation 1990, 2014
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