Technical Q&A's

PLAT 22 - Running out of TOC Space (1-June-96)

Q My PPCLink session tells me that I am running out of TOC space. Is there any way of knowing when we are approaching this limit?

A Since TOC entries are 4-bytes long, and are accessed via a signed 16-bit offset, you can have at most 16,384 TOC entries. A TOC entry is created for every item in the data section (i.e. read-only data, read/write data, zero-initialized data), every exported routine, and every imported symbol. If you have a lot of data, therefore, you can easily overflow the TOC section.

There are a couple of ways around this. One way is to split the application up into separate shared libs so each has its own data section. Another is to combine data items into a struct, which would then only require one TOC entry for the struct instead of one for each data item.

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