i've 32 uri adapters and i want to run 32 uri at same time so fist 7 uri is working, others isn't working, is there any limit to do this?

i've found a code in the linux server 

file name: chan_usbradio.c

in that file :

when change this number 32 to 3, only 3 uri is working but change 32 to 64 or something.. only 7 uri is working.. i don't understant that,

please help me.. thanks have a nice days

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