GDSX (Extended General Device Support) Manual
Design and Development
Extended General Device Support (GDSX) Manual—529931-001
2-61
MAXDCBPOOL
MAXDCBPOOL
This static parameter can be used to override the calculation of DCB pool space done
automatically by TSCODE during process initialization. In general, you should not
need to set this parameter.
The size that TSCODE calculates for the pool can be overridden by using a TACL
PARAM command to assign a value to the external name MAXDCBPOOL, or by
assigning a value to the internal parameter name in the
USER^INIT^CONFIG^PARAMS user exit. TSCODE uses the user-specified setting
unless it is determined that the pool size would be insufficient, in which case TSCODE
uses the value that it calculated.
If the pool size specified by this parameter is too large (more than 131,064 bytes), or if
the size causes the running total calculated for control block pools, the extended buffer
pool, and the extended message pool to exceed 16,777,216 bytes, an error message
is sent to the home terminal, and the GDSX process stops with abend error 020. The
configuration error message is:
10007 maxDCBpool or previous pools too large
TSCODE allocates the device control block (DCB) pool from extended memory. (See
dcb^template in the DCCBDECS file in Appendix C.) The size in bytes of the DCB
pool is calculated as follows:
DCB pool size =(DCBTBL size) + $LEN(DCB^TEMPLATE) +
(MAXTERMS * ($LEN(DCB^TEMPLATE) + (EXTSUSIZE *
2)))
One DCB is allocated for the #ZSPI monitor, making a total of (MAXTERMS + 1) DCBs
to be allocated. DCBTBL, an INT(32) address table that points into the DCB pool area,
is also allocated from extended memory. The DCBTBL size is thus ((MAXTERMS + 1)
* 4), because each address in the table requires 4 bytes.
The first $LEN(DCB^TEMPLATE) to appear in the equation is for the #ZSPI monitor.
The remaining area (MAXTERMS * ($LEN(DCB^TEMPLATE) + (EXTSUSIZE * 2))) is
for the other DCBs; (EXTSUSIZE * 2) bytes for application-dependent data is included
for each DCB.
Internal DEFINE
Name
CONFIG^PARAMS
Name Default Value Range
maxdcbpoolsize maxdcbpool^size (see following
equation)
Up to 131,064 bytes